I got a 6800 because I play alot of OGL games... doom 3, NWN, WoW etc However the X88 pro is pretty nice. Again though, at 333 I would just spring the extra few buck for a GT...
To me the choice is 6800 or 6800 GT.... There is a significant difference there. The X800 pro is faster than the 6800 vanilla, but not fast enough to warrant the price difference to me. The GT on the other hand gives you better performance 16 pipes, a more advanced core and more features.
I just don't care for the ATI cards this generation. I REALLY wanted to like them because I've always gone with ATI, but I just dont care for the price/perfromance/feature set I dont see any real reason to consider anything except 6800/6800 GT unless you are a super ATI fanyboy or need something for a SFF
Also, someone mentioned the step up program. In 3 months GT's will be cheaper and you can upgrade to a 6800 GT, if you need to. That's what I planned on doing and I still may, however they 6800 vanilla offers surprisingly good performance.