It's a great learning experience.
All you really need is:
1. A Phillips head screwdriver
2. Ability to use Google to solve your problems
I would recommend purchasing a DIY Kit from Newegg:
http://www.newegg.com/Store/MasterCo...=DIY-PC-Combos
A kit like ($300~) this:
http://www.newegg.com/Product/ComboB...752468-_-Combo
Pair it with a $100~ Graphics card of your choice and you've got a pretty decent gaming computer on a budget. Even without the graphics card if you're currently running a 5~ year old OEM computer you'll notice a significant speed difference.
Use alternative means to obtain windows or install a Linux distro (Ubuntu, Fedora, Arch, etc.). Some University/College/Schools might provide MSDNAA access to free and/or cheap Microsoft software as well.