From the Ground Up

After typical use, any computer will start to feel sluggish. Many people often mistake this for a virus, or some type of adware or spyware. However, the reality is that there is nothing attacking your computer, it simply just needs a tune up, much in the way a car does every several thousand miles. There are several programs, all free, which will help you tune up your PC to get it running like the day you brought it home – AVG Free, Ad-Aware, Spybot: Search & Destroy, and Disk Defrag. Each serves a specific purpose in helping to get your computer back into shape.

AVG Free
What many people don’t understand is that just because you purchased your virus scan, it is not necessarily better than the free alternative. AVG Free is strictly a virus scan – there’s no firewall. But, Windows Vista, what all computers are shipping with nowadays, has a built in firewall, so there’s no need for a second one to be installed. Additionally, AVG has no expiration attached to it. McAfee and Norton generally come in 1 year subscriptions, and cost upwards of $50. For nothing, AVG stays up-to-date with automatic updates every time your computer is turned on. You can also schedule automatic scans to be performed each day to make sure your system is clean. Performing a virus scan is the first thing that you should do if your computer is feeling sluggish. Even if you don’t realize it, there may be some infected files hidden, which are taking up system resources, and causing the rest of your system to slow down.
Website: http://free.avg.com/

Ad-Aware
Through typical internet usage, adware and spyware are bound to get on your computer – it’s inevitable. Now not all of it will make your computer constantly restart, or display 200 pop ups when you jump online, but it still needs to be removed. Ad-Aware Free is an adware and spyware removal tool. A system scan typically takes about 20-30 minutes, and will result in the removal of malware. This means that spyware, dialers, Trojans, bots, data miners, aggressive advertising, parasites, browser hijackers, and tracking components will all be able to be identified and removed from your system [1].
Website: http://www.lavasoft.com/products/ad_aware_free.php

Spybot: Search & Destroy
Spybot:S&D is a free antispyware program that scans both the hard drive and RAM for infections. It is capable of repairing the Registry, Winsock LSPs, ActiveX objects, browser hijackers and BHOs, PUPS, computer cookies, trackerware, heavy duty, homepage hijackers, keyloggers, LSP, tracks, trojans, spybots, revision, and other kinds of malware [2]. Spybot also has the ability to remove tracking cookies that may be malicious. Again, a typical scan takes about 20-30 minutes to complete.
Website: http://www.safer-networking.org/en/download/index.html

Disk Defrag
When your system saves a file, it is generally placed over many sectors of your hard drive. When you delete the file, the disk simply removes the sectors, leaving them blank. After a while, this leaves many “spaces” on your hard drive. Defragmenting your hard drive reallocates your files to take up the most contiguous block of memory. By doing this, it takes less time to scan the drive for a file, resulting in a quicker system. The time it takes to complete will depend on the speed of your processor, and how large your hard drive. You should try to defrag your system every month if you are saving and deleting large amounts of files.
Website: http://www.auslogics.com/disk-defrag