Your memory will allow you to get to 3.6Ghz (400fsb on the cpu). To go beyond that, you'll need to overclock your memory which probably isn't worth the trouble.
That said, I don't think I"d push it with stock cooling. A couple hundred Mhz maybe, like to 3.3 max is as far as I'd go with a gun to my head. Otherwise, I'd never OC anything w/o betting cooling. Just isn't worth the risk!
Spend $30-$40 on the Xigamet + Retention Bracket, or Sunbeam Core Contact (comes with a bracket, though it's not bolt thru but better than standard Intel pushpins).