If you want to buy a notebook with a C2D and you're looking at a MacBook because of their size I see a few road blocks:
1) MacBooks come with Core Duos, but not C2Ds. The new MacBook Pros come with C2Ds, but...
2) MacBooks are the only MacBook model that come in a 13" model. The smallest MacBook Pro is a 15".
3) The prices are ridiculous. $1,099 for 1.82GHz Core Duo, 512MB RAM, 60GB HDD and combo drive on the MacBook. The MacBook Pro has some nice specs, big 120GB HDD, 2.16GHz C2D, 1GB RAM and a video card, but starts at $2,000!
My Sentia with better specs than that MacBook was $1,279 with shipping. I configured a MacBook with 80GB HDD and 1GB RAM (to match my Sentia) and it was $1,249 before shipping. You can't even upgrade the processor or customize anything else for that matter.
Unless you're absolutely in love with the MacBook look and exact size, don't mind taking a Core Duo over a Core 2 Duo and want to pay more I'd say the Sentia is your answer.
The MacBook does have a 128MB ATI X1600 card, but if you care about gaming that would require more than the Intel GMA950 in the Sentia you wouldn't want a MacBook with a 1.83 Core Duo anyway.
So far this may all be just my opinion, but if you plan to run Windows on a MacBook **without** BootCamp... it doesn't work:
http://arstechnica.com/reviews/hardw...-coreduo.ars/7
The MacBook simply refuses to read the Windows install CD except for the Itanium version. Windows doesn't like the MacBook's firmware.