Sujanne - do you mean how much processing power to you need to do what you listed but not multibox games? If so the answer is very little. For standard office stuff, even very heavy use of standard office stuff, any of the current or last generation dual core CPU's will be fine.

Personally, my laptops have a T5500 a dual-core Pentium E2100 (I think?) and a T7300. Asside from gaming I can't really tell much of a difference in routine office stuff. I would avoid the pentiums (no relation to the old desktop processors) and celeron chips though, they just strike me underpowered CPUs.

Even for gaming, I used to use the T5500 for WoW (single boxing) and it did fine matched to an 7900gs video card. It's about 3 years old now so it's showing some age, but I can play WoW nicely - just have to turn down the gfx seetings a bit with a native 1920x1200 res display.