Some simple basic steps will keep your computer at peak performance, or revive it when it begins to slow down. If things simply don't function anymore and you're comfortable doing it, I always recommend a fresh install of OS (XP, Vista, Win7). I've known techs who wipe/reinstall religiously every six months or a year to keep everything clean and fast. For most end-users that's a bit extreme, so here's a quick tune-up guide:
1. Remove Unneeded Programs. If you never use a program or game anymore, why is it still on your system? Remove anything you don't need, especially anything with the word "search helper" or "toolbar" in it. Some things may not be listed in Control Panel's Add/Remove Programs, so check the Start menu for old applications' Uninstall shortcut.
2. Check system Startup. Lots of program creators love to gobble your Startup resources, which adds up and turns your booting and system tray into a big slow mess. To solve this, open MSconfig (Start-> Run-> msconfig-> OK) and uncheck anything you don't need to run at startup. If you don't know what something is, just Google it so you can make an informed choice before disabling it.
3. Disk cleanup. Over time, your hard drive gathers temporary files, setup files, and other miscellaneous garbage. This eats up disk space and slows down your PC. To solve this, simply click Start-> Programs-> Accessories-> System Tools-> Disk Cleanup. Select what files you want deleted, but I do not recommend the 'Compress old files' option if you care about speed. Then click OK, OK.
4. Defrag, defrag, defrag. For the love of all that is computerized, defragment your hard drive! After months or years of use, your system drive has scattered bits of data everywhere, and the hard drive grinds like mad jumping all over to gather the pieces. Just start it before going to bed (Start-> All Programs-> Accessories-> System Tools-> Disk Defragmenter) and by morning your computer will thank you. Once a month would be the minimum I'd recommend; if you can, once a week would be better. That way next time it will only take 20 minutes, not 2 hours, to complete.
5. Viri, Spyware, and Adware prevention applications. These are truly a double-edged sword. On one hand, they perform a valuable service. On the other, they can be a money sink to the uninformed and could slow your system worse than the possible problems. I personally do not use any resource-sucking resident scanner, but regularly give my system a full checkup instead. To use this method, my advice is to download, install, and occasionally run Adaware (http://www.lavasoftusa.com/products/ad_aware_free.php) for the spyware/adware removal. For virus checking, stop by Trend Micro's HouseCall (http://housecall.trendmicro.com/) for a complete online virus scan. Both are free, of course. If you want a 24/7 virus protection, I unfortunately have no free recommendations… not if you want to keep your PC quick and unbloated. I prefer Nod32 (http://www.eset.com/download/index.php), which does cost money- but they do have a 30-day trial.
6. Be Windows smart. Avoid problem-causing behavior. Randomly installing games bundled with ‘search helpers,’ toolbars, or advertising offers is just begging for a slow system. Whenever possible, avoid hitting “next-next-next-next” during unfamiliar setup programs. It’s okay to select Custom or Advanced Install to see what’s going onto your PC. Use your common sense to evaluate the optional modules. Do you really need a 20-day e-Music offer? Do you really need yet another search bar or Savings Center? The web is full of spammy advertising; why give it space on your personal computer? Using Internet Explorer and blindly hitting okay to unsigned ActiveX popups is another good way to convert your desktop into an uncontrolled billboard.
7. Don’t Panic. If things do get bad, remember these options. Print this if you have to. An hour of your time can stop months of frustration, staring games with the hourglass cursor, and save hundreds in computer ‘repair’ bills.