Quote: "Why? Because hardware manufacturers switch the interfaces so you are force to buy the latest technology."
In reality it's done to support a higher end bandwidth and keep silly people from putting unsupported hardware in the slot.
For example, a PCI socket is much faster than an ISA socket, but hardware made for ISA could never work in a PCI slot, even if the pin layout were the same.
As for processors, intel's been using lga-775 for years now, since the Pentium 4, and we're already on Core Quads with no mention of a new pin layout
It does make it harder for us computer builders, because we have to verify that the mobo we are getting is compatible with the processor we want to use, even though the Socket is correct, the northbridge also has to be compatible, which it often is not for certain processors. An example would be buying a dated mobo and attempting to use a core quad in it.
The 8400gs is not 2-3 series back, it's just the low end of the 8 series. It's completely directx10 compatible, and actually quite capable. I can play COD 4 on medium settings just fine. Try playing that on a geforce 4 sometime
I doubt it would run well on 6 series graphics card either. By the time you get into the 7 series, it's in many ways the same card, but without directx 10 capability.
But I agree with gamebird on the fact that a new computer is needed at this point. I wouldn't trust the hard drives or disk drives, or power supply either.
All that needs an overhaul. On any new computer you should be using sata for all the drives. Since you're likely using ide, it's all outdated.
You might be able to get by with using the same case.
Hurray for teh logd!