http://www2.ati.com/drivers/wxp-w2k-...7a-017086E.exe
I havent tried them myself yet (Just got in from work)
But the 4.8 beta's fixed shadow problems in Thief deadly shadows and also seemed faster so hopefully these 4.9 drivers still have these fixes and a speed increase to Doom 3 for ATI owners
Remember they are BETA though so use at your own risk..