I registered just to ask this question. It seems Phoronix members have quite some experience with different graphics cards under Linux.
Some background: I am using Linux on and off since Redhat 6.0 (those were the days of 2.2 kernels). My current card is a geforce 6600 AGP, previous was a radeon x1650 xt.
I am building a new rig for photo editing and some hobby opengl development. Based on an AMD platform (Phenom II X2, 4gb ram, 785g mATX mobo). The last part is the graphics card. Requirements are:
color calibration (this is not entirely card dependant, I know)
good wine support (but not a top prio, I do some light MMORPG gaming - eve online, guildwars, jade dynasty)
cheap (this is a huge factor) - sub 100 euro
Now I did some research on the internet with some google help. Most of the comments I read are about Windows based platforms or are ancient old (opengl 1.5 days).
So far I have a 9800GT 512MB in view. I can get a HD 4870 2nd hand from a friend.
It seems the nvidia one has better driver and developer support, however I have seen reports that their shader compilers are a bit on the benevolent side. They do accept things not strictly standard which later makes trouble for ATI cards. On the other side, I still remember fglrx problems I had.
looks like I will settle with the 9800GT and use the integrated HD4200 to test ATI compatibility. seems to be the best solution.
The 9800GT is certianly more then capable of handling anything that linux can throw at it right now with maybe the exception of Double-Precision in GPU computing, a GT200 card is required for that. This however will not be a real factor until mainstream user openCL apps hit the wild.