Probably the Cat's 4.3 or the Omegas based off of that would be best, that's what I'm using. Although I have no real reference to compare the 4.3's to with older drivers since I just got my 9700pro, but I'd recomend you always try to use the newest drivers, and they seem to work fine for me.
*edit*
Accidently put Cat's 4.2, I meant Cat's 4.3.
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