Well, you can't run MacOSX on your current machine, so if you get a Linux distro, get a current one, pick one that somebody here has recommended, or go to the linuxiso site that's in VoidMain's tagline.
When i asked not long ago about supported file types et c, the general consensus was that you can use different applications in Linux to do the same job as, say, Morpheus, Photoshop, MP3 player, whatever, you can get programs to do all that stuff, probably for free in Linux. Everybody says it's more stable and usually faster than whatever equivalent is in windows too.
As i understand it though, while some programs have been written for both windows and Linux, and often other OSs too (OSX, SunOS et c), a lot haven't, so to edit yr premiere and photoshop files, you might have to learn how to use a new program.
No hass to you if you're already thinking of ditching yr entire operating system.
I haven't changed to Linux yet, but i thought i'd just put in my $0.02 worth since i asked some of those questions myself, and got very good answers from the good folks here.