All my gear is Windows-based, meaning Windows 7, plus one Vista machine that's used as an audio server.
What's simply amazing to me is how much you get for $1000 these days, for example the HP HDX 18/dv8t series... it starts with an 18.4" screen, close to a terabyte of hard drive, Blu-Ray DVD player, HDMI, 4 USBs, Firewire, and on and on and on. If you watch the merchandising channels carefully, they are constantly changing small details in the configuration and packaging. It's often possible to get "last weeks" version for deep discount (
www.buydig.com).
One other caveat: it's usually way cheaper to buy through channels, rather than on the HP Website. Configuring your "perfect" PC will easily cost 20-30% more than simply buying a similar, or identical, unit through distribution. Basically, using the Website is an "experience" for which you pay dearly.
I've had zero problems with viruses or reliability in years. All the flack about PCs being this or that is from 10 years ago. Today's Windows 7/PC products are a huge improvement over the past, as is Office 2010.
A similar Apple laptop is close to $3000, which is triple the cost of the HP, except that Mac Book Pro doesn't have Blu-Ray, smaller disc, etc. The big advantage of the MBP is the excellent display (presumably an LG/Philips) which is definitely nicer appearing than those on the HP.
For use with audio, WASAPI gives bit-perfect output without any hassles.
I would however very much like to get a 17" MCB for audio review purposes. Some new digital audio products are oriented towards iTunes, and offer quite a few nice features.