I was in the same boat a couple months ago--just keep reading the forums and you'll get acquainted with this OC'ing thing... The e6550 can only multiply at 6 or 7. However, SpeedStep is an energy-saving feature which lowers the multiplier to 6 when you're not running many programs. So if your FSB is at 400 or 2.8 GHz (7*400); if idle, it'll go to ~2.4 GHz (6*400)
I'm still on the stock Intel HSF, and i've got my e6550 @ 2.80GHz (7*400; 400=the FSB) 24/7, my RAM still @ 400(DDR-800). Although, the timings are tightened to 4-4-4-12, from 5-5-5-15. I can get 3.15GHz(7*450) stable with temps at about 57-58C under load, RAM at 450(DDR-900).
Official temps. are on my system, below.