Before you open the case and start moving things around, here is a checklist of things you should consider. Back up your hard drive. Even if your upgrade plans do not include the hard drive, it is still a good idea to have a full backup of your system.
Accidents can happen, so be prepared.
Take a snapshot of your working system. Record all of the hardware devices installed on your machine as well as their configuration settings. If something goes wrong with your upgrade, you can either use the printed report to put your system back together as it once was or e-mail it off to a technical support technician. Clear your workspace. You might also consider moving your PC tower to a broad, well-lit surface that is relatively free of static.