Use Xbuntu, its basically Linux for starters. It is free and pretty easy to use though minecraft can be a bit of a pain to install. Though there is normally a quick and easy input on the console that can install stuff for you with no problem (i.e. steam). If you ever need some help looking for parts to fit into a budget let me know.
You said you have a "fancy cpu" what manufacturer and what model is it.. If the computer itself is old the motherboard might not have a compatible slot for it.
this is the cpu AMD FX-8350 Black Edition Vishera 8-Core 4.0GHz 4.2GHz Turbo, Socket AM3+ 125W FD8350FRHKBOX Desktop Processor when i get somthing i tell what it is and when i mean a ios it means i ment OS i didnt see the typo
Damn, that's good. Personally i use an AMD 6-core Vishera with around 3.5GHz. You might be able to rely on dedicated graphics instead of outright buying a new graphics card. Though if you do get something from the R9 200 series, compliments it nicely.