I may buy a Mac someday, but only because Microsoft has crossed over my threshold of tolerance for their antics. I hate being bullied, I hate their arrogance, I hate Vista and I hate having to learn a new interface every time that M$ issues a new OS. Can’t they tweak under the hood without redesigning the dashboard? BTW, I am typing this from a Ubuntu Linux box.
Before buying a Mac you need to test compatibility:
1) Make sure there are Mac versions of apps you need - obvious.
2) Make sure the websites you use are compatible - not so obvious and getting worse all the time.
3) Mac sure the people you do business with will not send you MS-Office files with Macros, etc.
There are workarounds including installing Windows in a VM on the Mac. But it is a pain in the arse.