lol... you guys
the gf FX lineup represents the ENTIRE new line from nvidia... the nv30 gpu is the one I think you are mentioning...
hardware wise... ati probably has the advantage... their card works to spec... the nv30 has some issues... not so sure anymore if it is hardware or software...
anyways... the gf FX 5800ultra is more programmable... but this will not result in it being better in scenarios with lots of shaders... its memory bandwidth will throtle it... it does make it a good choice for game devs though... and the card also supports higher color precision... though ati's card sticks to or exceeds the dx9 api...
raw performance... the 2 sets of cards are pretty much on a par...
when it comes to high res with AA and FSAA turned on... the gf FX has issues... perhaps driver related... perhaps hardware related... but it can't keep up...
if you compare apples to apples... ie... trilinear filtering to trilinear filtering... there is no comparison... the nv30 can't keep up... basically a fact...
lots of websites that benchmark these cards are told how to do it by the respective companies.. the problem being nvidia's suggested settings basically do not yield apples to apples comparisons and show their card in better light than it really is... ati also suggests different settings... but the difference being they have WHQL drivers and their cards operate @ a high color precision per the dx9 api ALL the time...
however... the nv30 is not a bad choice...it is NOT a bad card... it is a MASSIVE card and you will likely need a full size tower to fit it in... plan around it... the 9800pro is also longer than the 9700pro but still not quite as long as the nv30...
you will be fine going with either card... the nv30 is unlikely to retail on shelves @ stores... you will have to order online/preorder and pray you get one of the few allocated cards...
the nv35 is coming out soon and should take over the performance crown with many optimizations over the nv30... we'll know in a couple of months time..