Actually, the Pentium M (ancestor of Yonah/Core Duo) DOES come pretty close to high-end desktop Pentium performance. "Beats?" Maybe not always, but with a top GPU it could outrun a LOT of people's desktop gaming rigs. I don't have trouble believing that claim, having read the Pentium M review and head-to-head benchmarks at Tom's Hardware:
http://www.tomshardware.com/2005/05/25/dothan_over_netburst/index.html
"we were able to raise the FSB from 133 to 160 MHz without any trouble at all. The result was that our 2.13GHz Pentium M 770 ended up running at 2.56 GHz! At this clock speed, our two year old platform was able to beat the processor heavyweights Athlon 64 FX and Intel Pentium 4 Extreme Edition in all 3D games!"
Now, even ONE Yonah core is faster than a Pentium M--and the iMac/MacBook Pro have two cores.