I don't think compatibility should be a major issue with a Mac. I worked for 5 years or so at a multi-platform company. Everyone could get whichever platform s/he wanted. We ran Microsoft Word, Excel and PowerPoint; PageMaker for page layout; some fairly sophisticated FileMaker Pro database apps; Dreamweaver and Fireworks for Web development; Acrobat for creating PDFs and a few others. The only compatibility issues we ever had involved graphics embedded in Word documents, and those were few and far between. So, unless you have specific application needs that force you to Windows (the occasional Access database doesn't count; it runs fine under Virtual PC) that by itself is not a reason to go that route.

However, VPC is not practical for most interactive games. (The term "sucks" comes to mind.) Its overhead is too high. If you want to run an interactive game that requires Windows, get a system that runs Windows.