Apparently Romney is, as I imagined, a PC guy. From a Tech Crunch interview:

[Interviewer]: I guess that brings us to the most important question I have to ask you, which is…Governor Romney, Mac or PC?

[Romney]: I have a PC. My sons have a Mac and swear by it, but I have a couple PC’s.

[Interviewer]: So one of your sons is on Mac, or most of them are?

[Romney]: 3 out of the 5 boys I believe are on Macs, and they swear by them, but I’m a creature of habit, I’ve got my PC.

So there you have it, the boxers / briefs issue of 08.