Malwarebytes is a site dedicated to fighting malware. Malwarebytes has developed a variety of tools that can identify and remove malicious software from your computer. When your computer becomes infected, Malwarebytes can provide the needed assistance to remove the infection and restore the machine back to optimum performance.
Microsoft Security Essentialsr provides real-time protection for your home PC that guards against viruses, spyware, and other malicious software.
CCleaner is a freeware system optimization, privacy and cleaning 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. Additionally it contains a fully featured registry cleaner. But the best part is that it's fast (normally taking less than a second to run) and contains NO Spyware or Adware! :)
Use Defraggler to defrag your entire hard drive, or individual files - unique in the industry. This compact and portable Windows application supports NTFS and FAT32 file systems.
OpenDNS is the leading provider of free security and infrastructure services that make the Internet safer through integrated Web content filtering, anti-phishing and DNS.
Grisoft makes the AVG Anti-Virus system; free for personal use. (support forums)
Lavasoft's Ad-aware is a free multi spyware removal utility that scans your system for known spyware and scumware components and lets you remove them safely. (support forums)
Are you using broadband (DSL/Cable/etc.)? If so, check out Broadband Reports for help in testing and configuring your connection.
Hijack This: A general homepage hijackers detector and remover.
Microsoft PowerToys for Windows XP are additional programs that developers work on after a product has been released to manufacturing. They add fun and functionality to the Windows experience.