I've used and am quite familiar with both Mac OS X and Windows XP in PCs.
You mentioned the stability advantage of Macs and I agree - they are extremely stable...but, a PC taken good care of can be equally stable. Macs are pleasing to the eye as the interface of the OS is quite aesthetic and made simple for users.
However, there is absolutely no question in my mind that the PC reigns superior in all other aspects over the Macs because of the simple and undeniable fact that the PC/WindowsXP is a million times more complicated. The complications brings up the issues of stability, hacks, viruses, etc. but I'd give up stability and aesthetics in a heartbeat for all of those additional features. This isn't due to the fact that the Mac OS has less/inferior coding relative to Windows but instead, the Mac OS was coded in a way so as to intentionally block users from getting too advanced/technical, thus balking all access to highly technical maneuvers.
The Mac is so simple, in fact, that I learned the complete ins and outs of the entire OS in a matter of days. For Windows/PCs, on the other hand, it's endless. No matter how deep you dig, the OS is so complicated it's mind-boggling.
I believe, in your applications you mentioned, a Mac would more than suffice. Apple has software for all of your purposes - and good ones, at that. But, if in the long run you ever decide you want more advanced programs, features, or simply more programs from 3rd parties not available for the Mac OS, the PC is the only way to go.
I wouldn't pick a Mac for both worlds but rather concentrate on picking one or the other. Note that Mac running Windows isn't even a solid issue yet - who knows, there could be hordes of problems and it might not even be as fast as a Windows-dedicated laptop. Hell, even the Mac OS X has issues reverting back to Mac OS 9 back when I was using multiple OS's.
I'm sorry about my outlandish behavior - there's too much blood in my alcohol system.