Choosing The Right Power Supply
by Derek Vadala
Related link: http://www.firingsquad.com/guides/power_supply/
It's often really hard to find good information about building systems, since most of the material out there typically covers CPUs or video cards. Here's a good article about power supplies from the folks at Firing Squad. I've found that a lot of people don't even realize that an underpowered system can cause all sorts of annoyingly random problems.