SoftwarePatch is where you'll find loads of software and patch downloads.
DriverGuide gives you access to a great deal of drivers and other resources.
eXtreme Power Supply Calculator Lite v2.5 lets you check what power supply your computer needs.
FileHippo and Download.com are vast repositories of freeware and updates for your system.
From the AVG website you may download lightweight and reliable antivirus software - either free or full, commercial edition.
Basic edition of Avast is, like AVG, free and will protect your computer against viruses, trojans and other malware.
Comodo Firewall Pro is a free, yet very reliable and trustworthy firewall.
ZoneAlarm is another powerful firewall coming either free or, if you are willing to invest some money, as a full, commercial edition.
CCleaner is a small but extremely useful tool allowing you to get rid of all unnecessary files, temporary internet files and other bits that clutter and slow down your system.