His mobo does have PCI-E. But no, the ram isn't fine. If he were to get something like a 7600GT the lack of ram creates a major bottleneck. He'd have to upgrade to at least a gig (but 2 gb's is the best bang for your buck)
I would know. Aside from it being on a different mobo, it's the exact same setup I had for a month or 2. After all, it
was my hardware.

I upgraded to a 7600GT and still had to run everything lower on medium and stuff unless I wanted to sit for 10+ minutes, waiting for a game to load with stuff bumped up to high. And after it all loaded it'd take a good 5-10 more minutes of gameplay for the memcache to dump and the framerate to smooth out.
So what I'm saying is; No, throwing a 7600GT into his PC will not magically make TF2 run on all high with full framerate. Once again, I would know. I have a 7600gt in my PC right now, a C2D processor (E6420 @2.13ghz) and 2gb of ram. I play at those exact same settings, 1024x768 all high, and while I do have a stable framerate, it dips a lot in TF2. It can go anywhere from 20-70fps, but usually stays around the 30-50fps range.
I'm not saying that's a bad framerate or anything, I'm happy with it... But even if blaze had 2gb of ram and a 7600GT, the P4 would still chug on that game.