I installed a 2nd hard drive in my computer today. I didn't really need the space but figured I didn't want to ever worry about it so I just bought a 500 GB hard drive from Fry's (only paid $100 which was a pretty good deal) and went to open my computer to install it.
Installing a second hard drive is actually a pretty easy process which most people can do themselves You simply have to open up the chassis, screw the hard drive into a slot, find the power cord and the data cord and plug them in. If you have an older computer, it can be slightly more difficult, but with SATA drives, which most drives are these days, it is a snap. Boot the computer and your computer should recognize that you installed a second drive.
Of course, I find out that my stupid computer doesn't have a slot for another 3.5 inch drive, which is the standard size for all modern hard drives. So I had to go back to Fry's to go buy a sleeve to install the drive into a 5.25 inch slot. Stupid thing cost me another $20 (they did have some cheaper options but I went with this one). Nothing ever comes easy to me I guess.