Depending on the age and value of your PC, it may not be worthwhile to upgrade or repair anything at all. If your machine is more than three years old, we generally don't recommend spending more than a hundred bucks for RAM and a new hard drive. And once you reach the $200 price range, you're probably spending more than your computer is worth. With good now selling for as little as $500, it's reasonable to at least consider replacing your old system before spending good money on any upgrade or repair.