Yet the saying goes that the best things in life are free.

Why not look here if you're really interested in OS X vs. Windows operating systems?

http://www.macvswindows.com/index.php?title=Main_Page

Mac Pro is a over-powered machine, it using 2 server processors. In other words it is considered as a server computer.

iMac is a ripOff "desktop". Basically it is not consider as a desktop machine like normal generic pc. It using laptop board and everything (processor, gc, ram.. etc.) comes from laptop.

Ok.. that's the little overview of the iMac and Mac Pro. Now the question is what type of gaming? Hardcore like Oblivion or FPS games? Or just normal games like maybe nfsCarbon and etc? If hardcore, of cos that iMac cannot handle. You need that overpowered server-based machine (Mac Pro). If you really into gaming, i suggest you go buy a pc la.. Cos' the current Mac Pro graphic card is very no-no.. for hardcore gamer.

design programs on mac =design programs on pc
coding on mac = coding on pc
games on mac < games on pc
video editting on mac >video editting on pc (my opinion)

you can install osX on your PC, but i dont know how well it will run. sometimes it has problems detecting hardware. http://www.osx86project.org/

what you mean better in graphics? I don't think so, seriously. You can ask those "Pro" designers, 2D or 3D field. Both platforms (Windows and Mac OS) using same software. WHat i mean is both using Photoshop, Maya, etc..

The thing is iMac is using laptop board, which is considered low-end machine in the pc world. In gaming, graphic card is the most important thing. But for laptop gc, they sure lower down the clock/core speed due to the heat problem, the gc will become low/mid range. In other words, it is not really good for hardcore/FPS games, but normal games sure can handle without problem.

Ya. it is possible install mac osx in a generic pc. btw, i using that now But it is totally illegal.