I just completed replaying Half Life 2 and as a fan of gaming music in general (the music from Unreal and Unreal Tournament is my favorite), I realized the music in the game is pretty cool. After doing some research, I have found the program called GCFScape can be used to browse around inside the '.gcf' files located in x:\Valve\Steam\SteamApps. The Half Life 2 music is in MP3 format and is located in the 'source sounds.gcf' file. I also found the original Half Life music as well. This program will allow you to extract the music files to the location of your choice. I figured some of you might find this program useful! I haven't seen mention of this in the [H]ardForum before. You will need the 2.0 Dot Net framework installed from Microsoft to use this program.
http://nemesis.thewavelength.net/index.php?p=26
http://nemesis.thewavelength.net/index.php?p=26