I have used a Windows PC all my life until a few months ago, I got a MBP and absolutely love it. Most programs I used on PC exist on Mac, ex: Adobe Creative Suite, video converting software, and many more.
Now that STEAM has updated it to work with OS X, many games are ported over to OS X, such as TF2, CSS, PORTAL, HL2. There are also games like CoD for Mac and Battlefield.
If you have a Mac, you can always dual boot, or run vmware and install a Windows OS. I have used it myself to use some software that wasnt available on Mac.