This was originally posted on my other blog, Antithete, in two parts.
[NOTE: This is a Windows-only routine. For those of you with Mac or Linux routines, please leave me a link in the comments section, so that I can link them from here. Thanks!]
I have a weekly routine that I use to back up, protect, and update my computer - so it stays as shiny and usable as possible, and so that there aren’t so many ‘OH CRAP!’ moments. Like the kind that happen when your hard drive crashes and then you remember, as you stare at the black (or blue) screen of despair and death, that that last time you backed up your important information was three or four months ago. Maybe. And also you’re not sure where you put those disks anyway.
Then you think of all the documents and photographs and downloads and game data and chat logs you might have just lost, FOREVER, and the bottom drops out of your gut, and you feel like crying or screaming or giving up and walking away. Or maybe you just put your head down gently on your keyboard and sob quietly.
Never fear! A geek is here to help. 
In my arsenal are these free applications:
BitDefender (antivirus)
Spybot Search & Destroy (spyware killer)
SpywareBlaster (another spyware killer)
FileHippo Update Checker (an update checker, like it sounds)
Gmail account (optional - for doing backups, if you don’t have an external drive of some kind)
Gspace Firefox addon (for doing those backups the easy way)
CCleaner (hard drive and registry cleaner)
Defraggler (a defrag utility, although you can also use Windows’ native defragmenter)
Don’t get all click-happy and download those until you read (and bookmark) this post, because some of them may require you to restart your computer, and if you’re like me you might have already forgotten what you were doing when the restart is finished - and then you’ll be kicking yourself when your hard drive crashes, because THAT is when you will remember what you were doing.