If you find the thought of doing your own repairs or upgrades to your PC a bit intimidating, you're not alone. Nearly everyone feels that way at the beginning, but there's really nothing to worry about. Working on a PC is no more technically challenging than changing the oil in your car or hooking up a DVD player. Compared to assembling one of those "connect Tab A to Slot B" toys for your kids, it's a breeze.
PC components connect like building blocks. Component sizes, screw threads, mounting hole positions, cable connectors, and so on are standardized, so you needn't worry about whether something will fit. There are minor exceptions, of course. For example, some small cases accept only half-height or half-length expansion cards. There are important details, certainly. If you're upgrading your processor, for example, you must verify that your current motherboard supports the new processor. But overall there are few "gotchas" involved in repairing or upgrading a PC.
Nor do you need to worry much about damaging the PC or it damaging you. Taking simple precautions such as grounding yourself before touching static-sensitive components and verifying cable connections before you apply power are sufficient to prevent damage. Other than inside the power supply or CRT monitor which you should never open the highest voltage used inside a modern PC is 12V, which presents no shock hazard.
If you've never taken the cover off your PC before, you'll probably be amazed at how empty it is inside. Spend a few minutes comparing the photographs in this book to what you see inside the case, and you'll soon be able to identify all the important parts and what they do. From there, it's only a small step to repairing or upgrading your system by installing new parts to replace the old. Sooner than you think, you'll be an expert.
Can't find what you need? Try this upgrade and repair index.