I had a MacBook Pro 15.4" model that I later traded for a used Alienware m5500. I actually really liked the MacBook, but I needed money and came out with the Alienware at about $1000 less. The prices are probably closer together when you're talking new machines.
I loved the Mac for it's DVI port, thin and light design, and extremely quiet performance. I even overclocked the video (or rather bumped it up to "normal" X1600 speeds), and it didn't seem to run any hotter.
I used Boot Camp to install Windows, and it went smoothly. All my software was for Windows, so I didn't use OSX all that much. There were a couple of annoyances in Windows on the Mac that made me want to switch back to a native Windows machine. Notably, the right click functionality without an external mouse, which was impossible without some kind of key mapping kluge job, the backlighted keys not working, the battery indicator and power settings not working properly, no web cam, etc. These weren't huge issues, but they were annoying enough to me. Many of these might be fixed by now though for all I know.
All in all, if you're interested in "migrating" to OSX, the Mac is a great choice, but if you're going to use Windows primarily, I'd consider some of the small bugs before deciding. Good luck!