success,trades,sells,and buys :
1+ vouches for VI
1+ vouches for xXMuRpHXx
1+ vouches for Xmen*
1+ vouches for sosunluck
1+ vouches for chad911
1+ vouches for Vencreas
1+ vouches for IsReady
1+ vouches for CandaFrost
If you want to be different, this XPS 13 Developer Edition | Dell is a great choice. You'll be able to install Mac OS X on it (with less modification required than a hackintosh) and any Windows OS, too. It's gorgeous, fast, and portable.
The downside is the price and gaming performance. Games like COD4, for example, can still be run on high settings though.
Mac is ok, but if you plan on doing a lot... I'd go with PC...
If you don't mine too much, you can use bootcamp to Dual-Boot the Mac with Windows or Mac, by holding Alt when you turn it on. I used it for 2 or 3 years until i built this computer.. Honestly i'd recommend building, buying, a gaming PC..