ignoring the pretentious numbers of land grid array lubbers..
my own experience
ati2600 pro - not much to say, very nice card.
most need a bios flash- it is a mobility gpu , like the goofy rage lt pro of 1997 (?), but a chance to be colossal at 725mhz, and that is easily fixed, with techpowerup, and winatiflash, to take it out of the 110mhz mode and keep it at 300 mhz minimum. It is a complete flunk otherwise. This has been my favorite, after the flash, and the throttling is oh so very important...
both of these desperately needs aftermarket heatsinks
and anything with "DAC 400"
and, match the system ram speed with vid card. DDR-DDR2-DDR3 400mhz
and set the aperture to 32mb in bios, windows is still a complete jackass with it.
5th year this 2010, I have worked with several 845-865 chips, and a workstation 875. Very nice setups started at the 865, the 875 is just simply good from the get go. Maybe step up the board if you can fit a full atx.