CCleaner
http://www.ccleaner.com/
great registry cleaner, uninstaller, and windows cleaner-upper program.
AVG
http://free.avg.com/
AVG is one of the better and free virus scanners. Provided you don't spend your day surfing German Warez sites, it should be more than adequate.
uTorrent
http://www.utorrent.com/
cause...it's fun to steal shit. still one of the better BT clients, imo
Daemon Tools
http://www.daemon-tools.cc/dtcc/announcements.php
daemon tools is a great all-around program, it allows you to create virtual DVD/CD drives so you can mount image files. again, great if you pirate or rip games to your computer
EAC
http://www.exactaudiocopy.de/
THE BEST audio ripping program...if you rip CDs use EAC
Lame Codec
http://lame.sourceforge.net/index.php
You'll need the lame codec to rock cocks with EAC
Trillian
http://www.ceruleanstudios.com/
Trillian was, at one point, the best IM program...it continues to suck with each new release, but it's still superior to AIM
Filezip
http://www.filzip.com/en/index.html
Filezip is like Winrar...only free. Of course, you have uTorrent...soooo
As far as media goes....that's up to you. VLC, Media Player Classic, and Winamp are all viable options that surpass the competition.
http://www.videolan.org/vlc/
http://www.winamp.com/
http://www.free-codecs.com/download/...er_Classic.htm
And, of course, for when your computer gets infected:
http://lavasoft.com/
(ad aware)
You may also want to check out Mozilla Thunderbird for email....the FLAC codec if you are into serious audio, Image Burn for burning and making images, and Audacity for all around audio goodness.