He's only running emulators and videos. Which actually sounds a lot like my setup...I'm currently getting by on a 8500GT (apparently quite good for video decoding).
I really think a 3.2Ghz CPU should run emulators fine (assuming you're not trying to use PS2 EMULATOR?!). If you're experiencing slowdowns, it's most likely the bottleneck is somewhere else. Replace your ugly case, add an extra GB of RAM and run it in dual-channel if your motherboard supports it, plop in a cheap graphics card, and you should be set. A Windows re-install might also be in order...you've most likely accumulated a lot of nasties over 4 years.
If you're going for PS1/N64 emulation, you're not gonna need anything faster than an 8600GT GDDR3. If you just play 2D emulators, I'm not sure you'd even need a new card...I think they mostly use CPU anyway. I was running ZSNES full-speed on my 200Mhz IBM Aptiva with 2MB of video RAM.