I personally use Avira (
http://www.avira.com/en/pages/index.php) for my virus scanning needs. I haven't had one virus or malware/other crap between Windows Defender and Avira.
Newegg (
http://www.newegg.com) has good prices, great reviews, and great customer service.
Google (
http://www.google.com) obviously.
CCleaner (
http://www.ccleaner.com/) for general system clean up. Quick defrag every week and you're gold.
Audacity (
http://audacity.sourceforge.net/) for powerful MP3/WAV editing.
AltoMP3 Gold (
http://www.yuansoft.com/) for music conversions and audio disk ripper.
BitPim (
http://www.bitpim.org/) for cell phone customization, including ringtones. Useful for backing up your contacts and messages in case you lose your phone. Most stable on Linux, a bit shifty on Windows.
Mozilla Firefox (
http://www.mozilla.com), free web browser. Very secure, faster, and "lighter" in terms of memory use than Safari, IE, Opera, etc. Small plugins extend the basic functionality without slowing things down.
Google Toolbar (
http://toolbar.google.com) adds a Google toolbar to your browser, giving you quick access to the search function itself along with Gmail updates, PageRank of the current page, and Autofill fills in forms automatically.
YouTube (
http://www.youtube.com) great for passing the time or even researching projects.
