Mac. It's worth the extra money.
You get better security, stability, usability, many more configuration options if you want them, but you don't need to use them. Aside from games, you can get just about any software that's on Windows, or an equivalent. And there's a whole world of great free software that Windows users can't tap. There is a decent selection of games too, most of the really popular ones are available on OS X. You do have to wait a while for them to be released sometimes.
After using OS X on my main computer for like 9 months, I was working on my Windows box in my office and it was totally annoying.
I have never once had a system hang or crash, except when I installed some bad RAM, and when I spilled water on it once. I leave it on or asleep 24/7. In 9 months, the only time I rebooted was for some OS updates that forced you to reboot. And of course, without having to change any settings from the default install, you're immune to just about every security threat there is, except for if someone tricks you into running a malicious executable program that you have to download to your hard drive first. And even then, since there is no root user by default, you would have to sudo it and enter your password for it to do any real damage aside from wiping out your home directory.