Really may depend on style of game too as to whether performance issues are a problem. I've only played around briefly with PS2 emulation, but on my gaming PC (i7 950, HD6870, 18GB RAM, etc) it didn't have parity with a PS2 on stuff like Gran Turismo 3. Even at native resolution, it still slowed down and had massive audio problems.Frag Mortuus wrote: As far as ps2 and Wii emulation, both are pretty good as long as you have a gaming quality PC. I have a pretty good setup and seeing GC and PS2 ran at 1080p with anti-aliasing turn up all the way along with the various other filters you can add make those games look so good you won't believe your eyes. LoZ: Twilight Princess looks stunning. I never thought that game could look that good. But, like has been mentioned before, some game's dont run and other's have some problems. But, the emulator are constantly being tweaked and upgraded so they will get better over time.
There's a ton of potential there though, as 3D PS2 games (at least) can be made to look much, much better than they do on an actual system.