You may have read old fuddy duddy pages about this. Today, on say Windows 7 the multiple CPUs do other things some your app, even if single cpu can get the full attention of that lone cpu.
It's sad that folk fret so much on this. Even more so that some where past 2GHz and 2 cores the real bottle necks are the video card and hard disks.
I'm buying a new PC and I want an AMD Phenom processor, but can't decide between the faster (3.5 gHz) 2-core and the slower (2.9 gHz) 4-core model.
Mostly I surf the web, play mp3's, and play pc games. Of those activities, the pc games are the most cpu intensive application. And I'm not playing the most twitch-dependent games either, mostly older RPGs and strategy games, not bleeding edge FPSers.
My understanding is that 4 cores could or should equate to faster overall processing *if* the software is designed to take advantage of multicore processors. But with respect to my primary usage, would the 4 core really do anything for me that the (faster) dual core couldn't?