comparisons?
Many different video card performance comparisons have been done.
I'm sure you could find some relevant info over on
www.barefeats.com.
Personally, I don't agree with all the hostility against the X1900XT cards. I got one shortly after I bought my original Mac Pro 2.66Ghz machine - and I'm still using it daily. I even moved it over into my new Mac Pro 2.8Ghz box for right now. It's a faster/better card than the 2600, and FAR better than that lame nVidia 7300.
Yes, they have a lot of overheating issues. But THAT problem has many solutions. #1, you increase the fan speed of the fan that cools the card slots, using a freeware utility called "SMC Fan Control". #2, you either make sure the X1900XT card is kept free of dust buildup on its own cooling fan/heatsnk, or you buy a better replacement for it like the Accelero products (for about $30) and bolt that on. #3, Apple started selling a 2nd. revision of this card not too long after problems were first reported. Many people who initially complained about issues got their first rev. card swapped for a newer one by Apple, and that solved their problems.
Oh, and #4, you could even flash a PC version of an X1900XT 512MB card to an OS X version if you really wanted to. Instructions are out there on the net, and when I read them, it appeared it was even doable right from inside the Mac Pro itself. These cards are still found on eBay all the time for under $150 or so. (I point this out because I'd rather spend $120 or $130 on a PC version of the X1900XT off eBay and put in the effort to flash it for OS X than blow the money on a 2600HD card that doesn't perform nearly as well.)
i'm not happy either, i bought my MacPro to replace my dual G5 mid-late last year, and didnt get the 1900(thank god) as i was waiting for something newer... and now THIS!!!
I guess the question is, Are there real-life examples of how the 7300/2600/8800 compare?
Maybe a 2600 could be a worthwhile upgrade afterall.
Cheers.