They're up now. Looks like 8.583 is the recommened driver for both XP and Vista.
Once you narrow it down to Dell, ATI, XP x64 and SW2010 the picking choice is slim, the only one listed is the Precision 6400. SW should be certifying more drivers though I'm guessing they will not be certifying drivers for XP much longer. If you look for Dell, ATI, Windows 7 and SW2010 there are almost a dozen certified driver combinations.
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