I still have a Core i7-940 here. I didn't think I had a problem with it until recently, I was playing a game that listed the FPS and what it was limited by on the screen and about half the time I was CPU limited (didn't stop me from buying a new video card to help the times I wasn't CPU limited though). Then later that same week, I was doing some Bullet Dynamics calculations in Lightwave and my desktop with the i7-940 in it would take a while (multiple minutes), but the laptop I got last year was done in what seemed like less than 30 secs. I wish I knew what CPU the laptop had in it, I'll have to check.

I'll have to time each, but the difference was large enough that I started looking at replacing my desktop.