The X800 pro would easily outperform the 6600GT and vanilla 6800 in almost every game. The X800 pro can usually beat an AGP 6800GS, which is a 6800 with 350/1000 clock speeds. The 6800GT and 6800Ultra however are 16 pipe cards that are above the X800 pro.
You are right about the performance. 6800U = X850XT, X800XTpe, 7600GT for the most part, and those are easily above a X800 pro. But It's not twice the pipes; it's 16-pipes vs 12 pipes. Even the slower clocked 16-pipe 6800GT manages to pull out a victory against the X800 pro...that's why X800XL and X850 pro were released. they are both faster than the X800 pro and still basically just equal to a 6800GT. X800 pro fit's inbetween 6800 vanilla and 6800GT, or just barely above a AGP 6800GS (higher clocked 6800 vanilla).
You can see just how well the X800 pro does against many of these other mentioned cards. Note that even in these somewhat aging games, the 6600GT had a major weakness running fsaa at 12x10 and higher resolution. It's with the eye candy turned on the X800 pro would show it's superiority.
well thanks for all the help and info.... i guess that the x800pro is a pretty good card. all i am wondering about is SM 3.0 i know most ppl say that it doesnt really matter.. but i want to make sure.. so are there some games that i will miss out on due to the sm.20?
I honestly don't see Sm3.0 as a big deal in this level of cards. It basically amounts to not being able to use HDR in Oblvion, farcry, and a couple other games. But honestly, even owning a 6800U, I found it tanked running HDR in Farcry causing me to never consider gaming with HDR lower res and no fsaa. And although I liked HDR in Oblivion I only used it 50% of the time as you couldn't run HDR and FSAA at once on a GF6 (or GF7). I upgraded to a X1800XT, a card with more muscle that does well in Oblivion. And thansk to the chuck patch I use 4xaa and HDR while I play Oblivion.
Anyway, It's a tie breaking feature. Example a BFG 6800GS OC AGP vs X800 pro for the same price. Performance is very close, so if priced the same, then sure take the SM3.0 card as long as it competes in the games that matter to you. But by no means is it worth paying alot more for Sm3.0 or taking a clearly slower card just to have Sm3.0. I think it's a joke people push slower cards because they have SM3.0.
And by the time a game requires SM3.0, cards like the 6600GT and 7600GS will be obsolete due to lack of performance anyway. Kinda like the R8500 advantage of being a DX8.1 (PS1.4) and able to run BF2, while a faster GF4ti4200 could not being DX 8.0 (PS1.1) card. Who wants to run BF2 on a radeon 8500? So the ti4200 remained the better card to own reguardless.