Do your own computer upgrades and repairs. Adding a stick of RAM is as easy as plugging in a lamp and you can also easily replace things like power supplies, modems, ethernet cards or the CPU(main processor)
If you are going to upgrade your computer, be sure to shop at Newegg and Tigerdirect online. Also shop on eBay. If you have a Frys store near you, it is far better than Best Buy. Best Buy is usually the worst buy.