Windows OS or Mac OS, which One is Better?  

You might want to explain where you came up with that statement, because it's all wrong. Macs haven't been "four times more expensive than Windows" for a very long time. I checked Gateway's site; they sell a desktop for $509 with no monitor. That compares nicely to the Mac Mini at $599, which also comes with no monitor. Both are what I consider "minimally equipped" for their operating systems--4GB RAM for the Vista-equipped Gateway against 1GB RAM for the Mac. (I find Vista really doesn't run well with less than 4GB RAM; Macs work well with 1GB.) As for games...there aren't as many games for Mac, but there are games. Check out http://www.apple.com/games/articles/--that's just some of the games available on Mac. And if you don't like those games? Fine! Load Windows on the machine--it goes right on--and have the best of both worlds.

If you really want to spend money, go buy an Alienware PC--you can really jack the price on those up without thinking about it. A top-of-the-line Alienware costs about as much as a top-of-the-line Mac Pro (over $6000 for either one) and it won't work as fast because it's got one processor against two for the Mac.