This is a nice article, if you've ever wanted to do this!
Perhaps you've decided to take the plunge and build your own personal file server. But why bother with dedicated storage hardware when the desktop hard drives in your PC already offer up to 2 TB of capacity? Personally, I built my own file server so that I would have a backup of my data separate from my working PC.
Another good reason to have a networked server is easier access to data from multiple machines. For example, if you have an MP3 collection and want to listen to it from a home theater PC (HTPC) in the living room, it is easier to have all of your music centralized and browse straight to it over the network.