I switched to Mac about a year ago and haven't looked back. My computing needs are very low level by expert standards - a bit of skype, email, web browsing, photo management, music and podcasts, dvd watching and the odd letter/memo, spreadsheet and powerpoint. All of this is managed quite happily by the Mac with iWork and iLife and I keep a .mac account for the various on-the-road benefits it allows. The thing I like best is how good the macbook is for travel - it makes light work of hotel internet connections and skypes like a dream. It also gets good battery life for movies on the aircraft. So for me, the mac is perfect.
In my previous life with PC's, I enjoyed upgrading components and generally tinkering with the PC: If you are this kind of person then a PC is the only way to go. I also played a lot of games, and so did the kids, and once again, if this is the case, the PC has the legs of the mac by some measure. Finally, if you work in an environment where the office network requires various complicated or bespoke applications, then although Boot Camp/Parallels are an option, for a simple life a PC is probably better in my view.
IMHO what it boils down to is knowing what you want from the new computer. There will always be somewhat arcane discussions about the relative merits of windows/mac/linux operating systems on various hardware platforms. As a normal home user, you may assume that all of these OS's will work. Personally, I'd suggest a mac, because for me, it is the best solution at this time. You may be different...