Dual core, no question. It is not a matter of when multithreading happens, its allready started, and once you have the ability to multitask effectively, you will multitask. Hell having a virus protection program running and doing something else could wualify as multitasking in my opinion. Get the dual core, they are at a decent price point, in a couple of months they will be even better deal. If you ever plan to OC then get the x2 3800, if not, stick with the 4200. Plopping over $300 for a single core is a waste and shows little foresight, by 2007 they want to have quadcore CPU's, you better believe that programmers will be utlizing those cores. The era of single cores is effectively dead.