[jyl]

Mac.

The basic OS is very good. Extremely stable, far less "fiddling" than with Windows, excellent integrated search (Spotlight), convenience features (Expose, Widgets). Also far less problems with viruses, worms, spyware than Windows (in fact I've never had any such problems with OS X at all). I used to spend inordinate amounts of time fixing my PCs - clean installing Windows, etc - now I spend that time here on PP OT (hmm, a negative I guess).

The iLife applications are great - easy to use, work well together, basically best in class. I've mostly used iTunes and iPhoto, played with iMovie but am not a video buff. Safari is a very good browser.

Availability of other applications is very good. All the major apps are available for Mac (MS Office, Quicken, Photoshop, Firefox, etc). Almost all the major plugins are also. The only real exception is games, there are quite a few games for Mac but the PC gets them first.

Peripheral compatibility is good, sometimes you'll find office-oriented printers won't work so well w/ Mac. E.g. my dad just bought a Ricoh color laser all-in-one and is complaining some features don't work on his iMac. But H-P, Canon, Epson all support Mac well.

And now the Intel-based Macs make this really a no-brainer, just like Aurel said. You can install Apple's Boot Camp and dual boot into Windows XP, or you can install Parallels and switch between Mac and Windows on the fly.