After three years together, things just aren't the same between you and your PC. While friends play new games on their shiny new all-in-one machines, videoconference on Skype with their built-in webcams, and run the swank Aero edition of Windows Vista, your clunky old machine won't handle any of it. We've already addressed some simple software tricks for speeding up your computer before you go and start buying new parts, but the last resort - upgrading - deserves a guide in its own right. So here it is: a beginner's guide to upgrading your PC that explains what's out there, what it will do for you, and what to expect when you install it yourself. You'll want to further investigate some of the more complex upgrades before undertaking them, but if you're just looking to get an overview of the possibilities, you've come to the right place.