Norton Internet Security (Anti-Virus) 15 day trial
Antivirus, Antispyware, Two-way firewal,l Antiphishing, Rootkit detection, Intrusion prevention, Web site authentication, Eavesdropping protection, Confidential information management, Antispam, and Parental Control.
Norton Internet Security Website

CCleaner
CCleaner is a freeware system optimization and privacy tool. It removes unused files from your system - allowing Windows to run faster and freeing up valuable hard disk space. It also cleans traces of your online activities such as your Internet history.
CCleaner Website

MemTest
MemTest is a RAM reliability tester; it tests the ability of your computer's memory to store and retrieve data. By using it, you can insure that your computer's RAM functions correctly, an important diagnostic test for when you buy a new computer, install new RAM, or change the configuration of your machine.
MemTest Website

Ad-Aware
Ad-Aware 2007 Plus provides powerful protection that detects deceptive malware and spyware applications before they integrate into your PC and steal your personal information.
Ad-Aware Website