You shouldn't need any software to create FX, as such. There's plenty of sound libraries (online/CDRom etc.) already out there. I think one of the Magix 'Sound Essentials' discs should have what you're after.
For sound editing, on the cheap, I'd look at either Audacity (free) or Sound Forge Audio Studio 8 ($100?). Another freebie you might like to look at, for music/soundtracking is Magix Music Maker 2005 Silver, which is free after registration.
If you want to get into more complex music making software, none of the above will support MIDI, so you'd be better looking at Cakewalk or Cubase (I use Cakewalk - not cheap!).
If you want to make a 'Club Music'-type soundtrack, then Propellerhead's Rebirth RB-338 is now available for free, as well.
I have an XP3000+, 1.5gb DDR333, a 6600GT and I'm programming 3k text-based exe's?!