Modding is rather simple. Once you prctice you get good at it. Find an old crappy pc (like a 486 or pentium 1) and mod the crap out of it. Whats great is not only is that cheap, but it teaches you how to do one of the hardest things in modding-take a disgusting old school case and make it a work of art. Start with a paint job and cable managment, then go onto making a window and add lighting. When you are done this makes it easy to go onto somthing better. Scrap that case for anythign thats good (i.e. led fans and other lighting you bought and the hd if its a decent sized one) and transfer any mod supplies to the next case you work on. Just have fun and what helps me the most is letting the case reflect you.
Mobile-2.2Ghtz Core 2 Macbook, 4GB ram, 160GB HDD
Server-Dual 1.42 MDD G4, 1GB ram, 4 random hard drives.
PC-C2D 2.4Ghtz, Asus Commando, 2Gb ram, 3 hdd's in raid 5, 8800GTS.