*sings* It's the most wonderful time of the year...
Springtime of course! Which also means some time to do some spring cleaning. Not only is it a great time to get your house all sparkly clean, it's also a great time to get your hard drive nice and clean. This article has all kinds of great tips on how to do some spring cleaning to you hard drive. Please add any reviews of mentioned software, and by all means ADD YOUR OWN TIPS! This way all us geeks can have a squeaky clean computer to go with our sparkly clean house.... ok, or maybe just a squeaky clean computer 

Wellington Florida
Married
I try to atleast once a month do a computer cleaning. Since my computer has a clear side window I can see any dust in it so I dust in generally once a month. Its really easy if you have never done it. Simply remove a few screws in the back (generally like two) slide off the side panel and grab a can of caned air. Rule of thumb always remove the power cord from the back of the tower when doing this. Work the can air from the top to the bottom (making sure to hit the fans good) then once you hit the bottom blow any of the dust bunnies out. Put the side back on when your done and woo la dusted PC. Note: when your using can air don't turn the can upside down it tends to spit out moisture and that is not good. Also you don't have to stick the hose right up to it, hold it back a good 5-6 inches away. If you have never opened up a computer and your scared I did a while back take pics as I was cleaning mine out to show what the inside of one looks like. You can see that here: Computer Guts
Besides running my anti-virus (I scan that more then once a month) I run once a month my Adaware (by lavasoft) and my Spybot Search and Destroy.