The functions more or less stay the same, its the interfaces that change (or can change) - one reason why you cant have a choice of DX7,8 and/or 9 in DBPro. You can blame Microsoft for that.
Quote: "Hype Hype Hype. Have you no shame?"
Nope.
I'm not going to pick & choose the bits out of the DX9 SDK (takes too much effort), so here's everything :
DirectX
What's New in DirectX Graphics
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This section describes Microsoft® DirectX® graphics features that are new in the DirectX 9.0 SDK Update (Summer 2003).
HLSL Flow Control
The high-level shader language (HLSL) shader model has been extended to cover static and dynamic flow control and predication. This support will allow more complex shaders to be developed in HLSL. For more information, see Flow Control.
Precomputed Radiance Transfer
Precomputed radiance transfer (PRT) implemented with low-order spherical harmonic (SH) basis functions is a technique for rendering lighting environments with global effects such as interreflections, self shadowing, and subsurface scattering. For more information, see Precomputed Radiance Transfer or Precomputed Radiance Transfer Functions.
Tone Mapping for HDR Lighting
The real world has high dynamic range (HDR) lighting. You can now take advantage of a tone mapping algorithm that delivers a perceptually correct HDR lighting in a rendered scene. For more information, see HDR Lighting.
Effects Framework
The Effects framework has now been extended to help manage state changes across effects with the ID3DXEffectStateManager.
Animation
Many enhancements have been made to the ability to animate meshes. For more information, see the following:
ID3DXAnimationCallbackHandler
ID3DXAnimationController
ID3DXCompressedAnimationSet
ID3DXKeyframedAnimationSet
D3DXCreateCompressedAnimationSet
D3DXCreateKeyframedAnimationSet
D3DXCALLBACK_SEARCH_FLAGS
D3DXCOMPRESSION_FLAGS
D3DXEVENT_TYPE
D3DXPLAYBACK_TYPE
D3DXPRIORITY_TYPE
D3DXEVENT_DESC
D3DXKEY_CALLBACK
D3DXTRACK_DESC
Art Tools
The software development kit (SDK) includes new tools to view and convert texture files, and updated plug-ins to export .x files to 3ds max or Maya applications. For more information, see the following:
Texture Viewer
Texture File Converter
X-File Exporters
Samples
New samples are described in Graphics Samples.
Other Improvements
The ID3DXFont and ID3DXSprite interfaces now have more options to improve font rendering performance and to control sprite buffer storage and transformations. Also see available sprite rendering options in D3DXSPRITE.
The assembly-language shader reference section has been completely revised. It includes the instructions and registers in the table of contents. Each shader version has summary pages for the instructions and registers supported. For more information, see Assembly Shader Language.
The const keyword was added to many function (and method) parameters that are used by the function as an input only. This indicates that the parameter will not be changed when the function returns. There are too many instances of this change to list here. If you are having trouble compiling your existing application for DirectX 9.0, check the reference page documentation to determine whether you need to add the const keyword to your input parameter description.
DirectInput
What's New in DirectInput
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Version 9.0 primarily includes compatibility improvements for Microsoft® DirectInput®. There are no application programming interface (API) changes.
To learn more about new features in Microsoft DirectX®, see What's New in DirectX 9.0 SDK Update (Summer 2003).
Note For important information about using IDirectInput8::ConfigureDevices within a Microsoft Direct3D® 9.0 environment, see the IDirectInput8::ConfigureDevices Remarks.
DirectPlay
What's New in DirectPlay
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This section introduces new features for Microsoft® DirectPlay® 9.0.
New Features in DirectPlay
The DirectPlay application programming interfaces (APIs) are available for the Microsoft Windows® Powered Pocket PC 2002. See DirectPlay for Pocket PC 2002 for more information.
The DPN_MSGID_SEND_COMPLETE message structure has two new members that allow you to calculate the round-trip travel time of messages.
DirectPlay has a new service provider for network simulation. You can use the IDP8SimControl methods to test applications under a variety of network conditions.
DirectPlay has a new interface, IDirectPlay8ThreadPool, that allows you to manage threads in your application.
Applications can cancel all messages sent by a particular player using the DPNCANCEL_PLAYER_SENDS flag when calling IDirectPlay8Peer::CancelAsyncOperation, IDirectPlay8Server::CancelAsyncOperation, and IDirectPlay8Client::CancelAsyncOperation.
Players can receive their local player identifier (ID) in the DPN_MSGID_CONNECT_COMPLETE message.
Hosts can prevent DirectPlay from processing enumeration queries by setting the DPNSESSION_NOENUMS flag in the DPN_APPLICATION_DESC structure when calling IDirectPlay8Peer::Host and IDirectPlay8Server::Host.
Messages sent to a group with no players in it will now return DPNSUCCESS_NOPLAYERSINGROUP instead of DPNERR_GENERIC.
Packet signing is available for all DirectPlay traffic.
Applications can close immediately by setting the DPNCLOSE_IMMEDIATE flag when calling IDirectPlay8Peer::Close, IDirectPlay8Client::Close, and IDirectPlay8Server::Close.
DirectPlay 9.0 has improved defense against connection spoofing.
Use the DPNINITIALIZE_HINT_LANSESSION flag when calling IDirectPlay8Peer::Initialize, IDirectPlay8Client::Initialize, and IDirectPlay8Server::Initialize.
Packet coalescence is available by setting the DPNSEND_COALESCE flag when calling IDirectPlay8Peer::SendTo, IDirectPlay8Client::Send, and IDirectPlay8Server::SendTo.
Applications can tune the DirectPlay protocol using the DPN_CAPS_EX structure used when calling IDirectPlay8Peer::GetCaps, IDirectPlay8Client::GetCaps, and IDirectPlay8Server::GetCaps or IDirectPlay8Peer::SetCaps, IDirectPlay8Client::SetCaps, and IDirectPlay8Server::SetCaps.
A group owner's context value has been added to the DPNMSG_CREATE_GROUP structure.
If the DPNSESSION_NODPNSVR flag is not set in the DPN_APPLICATION_DESC structure when calling IDirectPlay8Peer::Host or IDirectPlay8Server::Host and dpnsvr.exe does not start, the call to Host will fail and return DPNERR_DPNSVRNOTAVAILABLE.
Less reliable connections should now perform better with improved DirectPlay protocol behavior.
Network Address Translation (NAT) support has improved. This includes the new IDirectPlay8NATResolver interface, which allows you to create a NAT resolver application.
DirectPlay now supports Internet Protocol (IP) v6.
DirectSound
What's New in DirectSound
The DirectSound application programming interface (API) has not been significantly revised for DirectX 9.0. However, many performance enhancements have been implemented.
In addition, the following changes have been made:
The maximum frequency of sound buffers has been increased from 100 kHz to 200 kHz, where supported by the operating system. (These higher frequencies are not supported by DirectShow.)
Frequency and effects controls (DSBCAPS_CTRLFREQUENCY and DSBCAPS_CRTLFX) can now be combined on buffers. Combining these flags makes it possible to have Doppler shift on buffers with effects.
Audio formats described by the WAVEFORMATEXTENSIBLE structure are fully supported throughout DirectSound.
The standard effect DMOs can process audio data in WAVE_FORMAT_IEEE_FLOAT format.
The standard effects support parameter curves (when hosted outside of DirectSound) without having to call IMediaObjectInPlace:: Process on them repeatedly in very small increments.
DirectMusic
What's New in DirectMusic
The DirectMusic application programming interface (API) has not been significantly revised for DirectX 9.0. However, many performance enhancements have been made. The most significant of these is a new low-latency DirectSound sink, which enables DirectMusic to attain much quicker response when using audiopaths that play through the software synthesizer. This enhancement is of particular interest to sound designers and composers who want to take advantage of the rich DirectMusic feature set but who also require low latency for sound effects. For more information, see Reducing Latency.
Several new features have been added to content created in DirectMusic Producer. For example, streamed waves in wave tracks can now be looped for the easier creation of ambient sounds, and looping can be done in clock time so that looping waves are not affected by tempo changes. For more information, see What's New in This Release in the DirectMusic Producer Help.
A large library of DirectMusic styles has been added to the SDK, along with an application for auditioning them.
In addition, two new tools have been made available in the binDXUtilsAppWizard folder of the SDK installation:
DMToolWizard.awx is a wizard for creating DirectMusic tools.
AEDMOWiz.awx is a wizard for creating effect DMOs.
Quote: "The Torque Game Engine is a far better value than TrueVision3D"
And almost impossible to try and program with.

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