Oh yeah that machine's gonna be a biatch. You better not dream about bringing that thing to Trini any time soon it just might get ninja'd.
W1n's got a good point, but I think that as long as developers ensure their products run on both platforms at least on almost the same level, everything should be ok. For example, in an Nvidia sponsored game, it could run, lets say, 3-6 fps better for the most than an ati part.