It's 256 bits for many cars now, so that's not a valid argument. If there are emulators being built (and why wouldn't there be), then I'm certain those doing it would be keeping it quiet as otherwise Sony would kick their asses.
As usual though it will take a PC with many multipliers worth of power over the PS2 and I've yet to see an emulator of any machine made in the last 8 years that runs faultless. Probably by the time the PS3 is out though, you may see a half decent one making a (semi-)public appearance.
I'd personally much rather just play on my PS2 which costs less than a high end graphics card, and with GT3 and GTC both platinum and the PS2 being a DVD player to boot, I can't really see any reason why anyone would bother with something half-decent. Heck even if you buy a TV card along with it to capture screenshots and video, you're still saving on one of those graphics cards that's outdated in less than 6 months anyway.
Just hook that PS2 to your Widescreen TV, stash in a nice Force Feedback wheel (just $50 for the great Logitech Wingman FF USB, that can also be used on PC) and enjoy the ride.
Better still, plug in another wheel and play with 2 (we do six player iLinking over a firewire hub, and we don't know what lag or pingtimes mean, if you catch my drift).
For me, as a programmer and general IT minded person, the PS2 is like a professional holiday - there's just so little thinking involved, no tweaking, no silly time-loss in figuring out the best settings (other than those of the cars of course), no unfair competition because someone's machine runs the game faster (or slower!) than someone else, etc.
Go on and keep investing in PC hardware if you're crazy about games like Unreal and Quake, but if you're serious about Gran Turismo, there's no alternative to owning and driving a PS2.
