This guide is a compendium of programs/locations where you can access free software that will help protect your computer from things like viruses and trojans and so-forth. This guide also contains some tips and tricks contained in windows that will help you utilize your computer's full potential.
Anti-virus programs: There are several programs out there that people will pay a lot of money for such as kaspersky, macafee (dear god.. *facepalm*), etc. There is absolutely no reason to pay for antivirus protection. Here are some programs that you might want to look into.
Malwarebytes Anti-Malware - Malwarebytes : Free anti-malware, anti-virus and spyware removal download
Just download the free version, it actually works pretty well.
Combofix - Bleeping Computer Downloads: ComboFix Download
With this one, you're going to want to install, then boot up your computer in safe-mode before you run the program. Also, make sure you have administrator privileges when you run the program.
Spybot S&D - The home of Spybot-S&D!
This has a great integrated feature that you can install with the program called "Tea-timer." Whenever a change is about to be made to a part of the registry, it will notify you and ask if you want to allow the change or deny it. Also, if you set your program to "Advanced Mode," there's a nice GUI interface where you can look at all of the programs that run on start-up. It provides a lot of help when you find a virus and you're trying to get rid of it.
ESET NOD32 - Free Antivirus Download from ESET
This one is my favorite. Someone obtained the algorithm to generate the serial keys for this program, however, they are all trial activations. Basically, you get all the features of the program, but about once a month, you have to go obtain another key from the site and update your program. The website where these keys can be found is NOD32 password and nod32 username | NOD32 Update | powered by nod325.com
HijackThis - http://free.antivirus.com/hijackthis/
Another free software, it will save logs of what it does in a text file for you after scans finish. Very useful in detecting pesky things that don't show up on many other software.
Tips & Tricks:
System Startup Apps (Windows) - click on the start button, run, and type in "msconfig" without the quotes. A window should pop up and you want to move to the tab called "Startup." Here, you will see all of the programs that are designated to run when your computer turns on. Several of these can be turned off, but be careful as you might turn something off that will mess up your computer the next time you boot up. This list can also be accessed through the Spybot program, but this is for people who don't have that program.
Increasing Bandwidth (Windows) - As many of you probably don't know, windows automatically allocates a small percentage of your bandwidth to allow for windows updates to run "efficiently." Personally, i don't ever use windows updates unless i need to in order to run a new game or program. Click on the start button and once again, go to run. This time, type in "gpedit.msc" Navigate to Local Computer Policy, Computer Configuration, Administrative Templates, Network, QOS Packet Scheduler, Limit Reservable Bandwidth. Double-click on "Limit reservable bandwidth and click on the properties option. You want to make sure that this feature is enabled, but where the amount of bandwidth that is reserved, you want to change it to 0% this will effectively recover a percentage of bandwidth.
Blocking adds w/firefox apps - An application for firefox was created to help the blocking of ads and pop-ups while browsing the web. Either go to firefox's website and search for the application "AdBlock Plus", or if you're using Firefox 4, you can simply search for the app by clicking on the Firefox button and then "Add-ons". A new tab should open with a nice search engine to search for firefox apps. You can also configure this app for specific websites that you may frequently visit.
EDIT: I tried as best I could to change font colors to make the guide more readable.