I've done a few NVidia cards, although admittedly I find ATI cards MUCH easier to flash as a general rule.
In any case, I'll see if I can find a cheap 4200 on Ebay to play around with...and maybe a 4600(to replace my dead Mac edition) while I'm at it.
If I get a chance, I need to play around with this one too. The fan makes a horrible racket on it, but I think I think I can transplant the fan off my dead Ti.