First, especially for those that do not want to be "security experts" as required in the Windows world, Mac is safer. If your parents ask what to get, say "Mac". It will ultimately save you time from being their tech support.
Second, the new Intel Macs are on par with the windows machines now. They are now running the same processors and are being kept up with the Jones's.
Third, options. My Macbook runs OS X and Vista on their own partitions via Boot Camp. I am running XP and Linux (ubuntu) virtually via Parallels. One laptop, One world. You can not beat it.
Last, the experience. The shareware, the unique apps, the look and feel, everything that is Mac. You can not get the fit and finish on a windows built machine.
Do yourself a favor and go Mac. You can always go back....on the same computer.