Windows: Crappy, slow, virus infested, but almost everything can run on it and it is also the most popular and most favored
Mac: Fast, smooth, not nearly as many viruses, but isn't compatible with very much (that is NOT Apple's fault - it's the designer of the program's responsibly to do it) and is rather rare and unliked
I personally would take a Mac that runs Windows as well. That is a huge advantage as then you can have a Mac AND Windows on one fast computer. Windows can't do that >:D and if you're not gaming then yo don't even need Windows.
You're handicapped. Macs are close to just as compatible as PC's. Steam, Minecraft, Blockland, various other games, all are being made in Mac version as Mac's start to grow more popular. Rare my ass, 1/3 of the blockland community alone uses mac. Apple sold 4 million macbooks in 2010 alone.
It's easy as stuff to run Windows on a Mac if you really want to. There's software for it, there's a BUILT IN PROGRAM FOR IT CALLED BOOT CAMP. And plenty of people use Windows for not gaming. Windows is known for being business oriented primarily, and it just so happens most games are built for Windows because it's easier. Also, the idea caught on a while back that Apple wouldn't make it in the long run. People were wrong.