Macs themselves aren't any different than a PC. the hardware in them is basically the same. You're still using an intel processor, and you're still using AMD/NVIDIA gfx cards. Thus, you're basically buying a heavily overpriced(and underpowered as far as value per dollar) PC, with what is essentially a locked-up non-free distribution of a free operating system loaded on it. What i mean by this is that Mac OSX is based off of linux, but linux itself is FREE.
anywho, you can build your own Mac out of a PC. and believe it or not...it'll do everything that the IMAC you're thinking about pissing money away at...but it'll be able to do it better, faster, and more efficiently!
the guy above is 100% right in his post.