A 260, 280, or 4870 of whatever flavor will be plenty to handle UT3 at decent settings, SM, though you didn't say what your resolution will be (1680, 1900...).
If I were building for UT3 as one of the main titles to play and wanted to spend more, then I'd put the extra $70. into a Q-core or faster drive setup, etc., not the 285. But that's just me.
OTOH, the E8600 should be enough as well, especially if you crank it up some under the Noctua.