I agree with OTT_B. Without going into the specifics, for multi-tasking & allround good performance, a quad-core is the way to go.
If you were solely a gamer, my advice may have been a high-clocked dual-core, like an E8600 (arguably the best dual-core that will ever be made), but the higher end quads aren't far behind in this regard.
Please don't obsess too much about the cache & other things - not really worth it considering you've chosen one of the best quad-cores of the last generation. Get it, use it & enjoy it :-). G