I honestly think anybody who tries to say one make is better than the other is talking out their bum
I know this, as for several years I championed ATI cards, only to see Nvidia take the lead, then ATI again, then Nvidia, and so on. So yes, that made me a one time bum talker
Just go for the best bang for the buck at time of buying, it really doesn't matter what make it is.
I'm currently using 2 x ATI 9800 Pros, an Nvidia FX5700LE and an Nvidia FX5600 256Mb. They are all good, imo.
Soon to upgrade to an Nvidia 6600GT, cos I ain't spending no more than £120.00 on an AGP card before I eventually upgrade to SLI.
As for ATI Catalyst drivers having to be tweaked for certain games, I'm running Far Cry and Doom 3 on one of the 9800 Pros, latest drivers, no probs at all, games run smooth, so I think the view that some games run better on Nvidia cards is, frankly, complete cobblers
And if you don't know how to tweak your video drivers, then you shouldn't even be fitting your own video card
And G-Man: For your budget, the X800XL256 is a good choice, go for it.