In no particular order. If it's free, it's a link to it. If not, you can be resourceful :)
UNFINISHED still. Also, this is targeted mainly at XP, since I don't use Vista/7.
Screen Recording
Camstudio (http://sourceforge.net/project/showfiles.php?group_id=131922) (desktop etc, NOT games)
Fraps (http://www.mediafire.com/?4dlnwku11wj) for game recording
CD Ripping, Music Conversion / Management
CDex (http://sourceforge.net/projects/cdexos/files/cdexos/CDex%201.70%20beta%204%202009/CDex-win32-1.70-b4-2009.exe/download) - CD ripping
dBPowerAMP Music Converter (http://www.dbpoweramp.com/dmc.htm) for converting between formats. Go to the codec central area for extra codecs
MP3 Tag Tools (http://massid3lib.sourceforge.net/) for managing ID3 tags
SUPER (http://www.erightsoft.com/SUPER.html) - More newbie video encoding/converting
MediaCoder (http://www.mediacoderhq.com/) - Advanced video converting (unfortunately somewhat spam-ware now)
Codecs
CCCP (http://www.cccp-project.net/) Codec pack to get playing every video file out there up to speed
Quicktime Alternative (http://www.free-codecs.com/download/quicktime_alternative.htm) and Real Alternative (http://www.codecguide.com/download_real.htm) - This and CCCP = perfect playback support in DirectShow
Media Playing
VLC (http://www.videolan.org/vlc/) and Media Player Classic Home Cinema (http://mpc-hc.sourceforge.net/) for playing videos.
Winamp 2.95 (http://www.oldversion.com/download_Winamp_2.95.html) for music. [placeholder for plugin/skin pack]
Piratan/Downloading
uTorrent (http://www.utorrent.com) - torrents of course
Cabos (http://cabos.sourceforge.jp/) - If you MUST use gnutella (network limewire uses) then use this client
Songr (http://songr.co.cc/download) - Tool that queries mp3 search engines to find music you want, you will fall in love
System Management
Defraggler (http://www.piriform.com/defraggler) - Don't use that piece of crap windows defragger, this is better.
QT Tab bar (http://qttabbar.wikidot.com/) - Like firefox's tabs? Wish windows explorer did that? Then get this.
Bandwidth Meter (http://file.xtreme.googlepages.com/bm.html) - Keep track of your bandwidth usage
Taskbar Shuffle (http://www.freewebs.com/nerdcave/taskbarshuffle.htm) - drag and drop your taskbar items to rearrange them
TeraCopy (http://www.codesector.com/teracopy.php) - Replace the default file copy system with this. Tired of a 5,000 item copy stopping because of ONE problem with ONE file? Get this.
CCleaner (http://www.piriform.com/ccleaner) - Tidy up crap that accumulates.
TweakUI (http://www.microsoft.com/windowsxp/Downloads/powertoys/Xppowertoys.mspx) - Customise many nuances, lots of other good tools on that page too
XP-Antispy (http://www.xp-antispy.org/index.php/lang-en) - ignore the shitty name, it's got some nice tweaks and edits, it's similar to tweakUI above
System Management - Information
Speedfan (http://www.almico.com/speedfan.php) - Monitor temperatures and in some cases control fan speeds.
PC Wizard (http://cpuid.com/pcwizard.php) - The grand daddy of system info tools.
CPU-Z (http://cpuid.com/cpuz.php) - CPU Info
GPU-Z (http://www.techpowerup.com/gpuz/) - GPU Info
Editing, Reading, Opening, Formats
Sumatra (http://blog.kowalczyk.info/software/sumatrapdf/download.html) - PDF Reader
Audacity (http://audacity.sourceforge.net/) - Audio Editing
Notepad++ (http://sourceforge.net/projects/notepad-plus/files/) - Advanced text editing, syntax hilighting
can I recommend OpenOffice? I know my PC shipped with a copy of Microsoft Office, but it was a trial version and I can't edit anything in them.
Here's the link. http://download.openoffice.org/other.html#en-US
i don't use as many as those but i can recomment
Foxit reader for PDF's - http://www.foxitsoftware.com/pdf/reader/
Sandboxie - http://www.sandboxie.com/
Foobar2000 - http://www.foobar2000.org/ (I only use this when i want to be nice to RAM)