Keep your PC clean and tidy-for Free!

Avira Antivir is really fantastic protection. It has all the features and resoruces of Norton or McAfee, but there's no subscription fee. Scans run fairly quickly, and don't use an unholy amount of system resources. Avira also has an advanced user feature that allow you to exclude items which is a plus for gamers as some game components can result in false positives. Updates are daily, and there is a scheduled system scan option as well. The free version comes with a nag screen with each update, but updates are typically only once a day, so it's not overly annoying.

ASC is almost an all in one solution. It cleans your registry, defrags, cleans cookies and temp files, AND has a lot of other features included all in one program. Notable extras include Game Booster (shuts down all non essential processes to make games faster and diminish lag), a Start Up manager, a Shortcut Fixer, and Smart RAM, which monitors usage and frees up memory when needed. Some of the utilities in ASC require you to buy the full program, but you really don't need them all. The best part is that cleaning is quick and easy, and doesn't use a ton of resources. Auto updates and scheduler are disabled in the free version.

CCleaner is a nice little easy to use, quick to scan antispyware utility. It cleans up all junk files that can accumulate on any browser(s) you may be using. The UI is self explanatory, so there's little need for me to elaborate  here. :)

I'll be honest, whenever I've used this program I've never come up with anything more serious than a few tracking cookies, so I have no idea how well Malwarebytes' works. It has a very good reputation though, and I trust the opinions and observations of people who have used it to remove unwanted maliciousness from their computers. It's easy to use, however, a complete scan takes a LONG time, so I suggest using the quick scan, unless of course you think you may be infected.

I've had Spybot S&D on hand for many years. It was created back in 2000 by Patrick Kolla. Apparently, he had gotten some kind of nasty adware on his PC and needed to get rid of it, Being a student of applied computer science he decided to create his own program. Now Safer Networking Ltd (the company behind S&D) offers a decent variety of other programs in addition to this one, and they are all completely FREE. That means no locked features, and no nag screens. Spybot isn't notorious for being quick or resource friendly, but it is a necessity if you do a lot of downloading or "surfing the net." S&D also has quite a few nice tweaks which help with things like locking your HOST file, among other things. After installing it, the program will ask you to make a registry backup. I suggest you do so just in case. It also has a feature called Tea Timer which alerts you of various changes you may otherwise be unaware of, such as registry changes or if something tries to change your homepage address. I personally don't use Tea Timer as it can be very picky and has a habit of nagging at inopportune times.