Requirements

The best processor you can get in your dirty hands!
That's mainly all, because the main problem is the speed and as better as your processor is as better speed you'll get.
Gfx card isn't that important and afaik your Geforce 2 would be enough to get nearly close DC gfx. Okay, some games you can't play, because the Chankast gfx plugin has a geforce bug, but that doesn't matter!
But all these requirements will decrease in near future because Chankast is only an alpha version, keep that in mind!

Right... btw: you should update your sig, when you've got your new PC...

MG = MB? catch = cache?
Gotta say I'd prefer an athlon, though, but what's done is done. Everyone stick to what they think is best.

What do you guys think would virtually be the time to expect like 80% of the games being emulated in a decent (30fps+) speed?

Kinda cannot wait to play Shenmue...