8 times out of ten, people with Macbooks will: 1.) Have some money to spend. 2.) Label themselves as "not computer people". 3.) Be of the persuasion that Macs can't get viruses.
And nine times out of ten Windows users are practically computer illiterate, what's your point?
(BTW, my point here is that I know more developers (when only counting those who have some kind of choice, if you're working for a bank that mandates Windows 2000 Pro on all developer desktops because it's corporate policy then you're not really interesting in this case) who use Macbooks/iMacs/Mac Pros running OS X than I know developers who use Windows Whatever)