From what I recall on earlier tests, STALKER has been improved at least.
I don't fully understand the AA settings meaning, but can tell you wide tent looks very good AA, 8x with 16x wide tent is very nice.
Any amount of AA still has a large performance hit (in 1920 x 1200 at least), but the actual performance hit between 2x (box) (the lowest) and 8xwith 16xwide tent (the highest) isn't as big as you may imagine.
Some figures from my testing HD2900XT 1024mb @ Stock, E6600 @ 3.5 ghz:
IL2 Sturmovik 1946:
Res 1920 x 1200
AA setting 4xaa 8xwide tent (control panel)
AF setting App controlled (control panel)
In game setting maxed, perfect settings with water mode 2.
Avg: 53.629 - Min: 19 - Max: 118
FEAR
Res 1920 x 1200
AA setting 4xaa (in game)
AF setting 16x (in game)
In game setting maxed (except soft shadows)
Avg: 53 - Min: 21 - Max: 119
STALKER
Res 1920 x 1200
AA setting mid way (in game slider)
AF setting max (in game slder)
In game setting maxed
Avg: 61 - Min: 26 - Max: 247
3DMark06
Default settings for app and control panel, IE no LOD reductions to score more

11315 (I think 12k+ stock shoulkd be possible, but there is a major slowdown for a second or so on the flying boat test, when the dragon comes out of the water, I presume a driver update will cure that soon).
3DMark05
Default settings for app and control panel, as above.
19894
X3 Reunion Demo/Bench
Res 1920 x 1200 4xAA 16xAF in demo
Settings maxed
Average 58 fps
I did need to add "-nosysteminfo" to the command line to get 05 and 06 to run.
Other opinions so far, the drivers still need some work IMO, but past experience shows normally ATi do well sorting drivers.
I am dissapointed with IL2 Sturmovik performance, I would hope that can be improved in newer drivers, it is an older title, but is pretty demanding still with all the eye candy, but those figures are not much above the X1900Pro.
Other games obviously are much faster than the X1900.
Overall, in comparison to my 8800GTX OC2 it works out around 20-25% slower, as it cost 25% less thats fair enough.
