it's rather easy.

remove and replace the stock harddrive(or reformat it)
install any other operating system. linux and BSD side it's usually integrated on install.
windows side winrar is excellent

one thing to note, check stuff like WINE and the like it's not THAT hard to get certain windows programs running under *nix. I know WINE works in most BSD based OSes and OSX is basically just a rippoff of Free BSD with an altered hybrid kernel.

MacOSX - The Official Wine Wiki
have a read should help.

and you'll have to forgive me. I have this tendency to think that just about anyone using OSX is absolutely incompetent with computers and I probably come off as such. It's my hobby, I expect everyone on the internet to have enough skill to make their way through a command line interface to get some stuff done and the vast majority do not.

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system: Intel Core 2 Duo e6400 @ 3.6GHz; 4*1GB RAM(micron D9GCT) @ 450mhz(DDR2-900) 4-4-3-8; Enermax Liberty 400AWT PSU; nvidia GeForce 8800GTS 640mb (660mhz core; 2120mhz mem)
OBAMA and BIDEN - 'we fight for you, blah blah we fight for you', theres only one man in this election that has fought for you, ONLY ONE and its not Obama.