I've been passed the "musical baton" meme by the Digital Medievalist. My responses are:

Total volume of music files on my computer: my iTunes folder is 63.77 GB with 14,250 tracks (songs, movements, etc.). I keep them on an external 160 GB hard drive. Most are 128 kbps MP3s, though I recently started using 160 kbps AAC.

Last CD bought: That would have to be the new Dream Theater album, Octavarium, which I actually ordered at the end of April. It was released yesterday and is in the mail now. I suppose that doesn't count the albums I've purchased from the iTunes Music Store, of which Count Basie & the Kansas City Seven (iTunes link) would be from last week.

Song playing: "Steel Guitar Rag" by Bob Wills and His Texas Playboys (1937). One of my favorites.

Five songs I listen to a lot, or that mean a lot to me (mostly that I listen to a lot):
• Metallica, "Master of Puppets" (duh)
The next four are what iTunes tells me are the top four most-often played songs in my library. Don't ask me why these seem to be my "favorites"
• Stormtroopers of Death, "Anti-Procrastination Song"
• Megadeth, "Rattlehead"
• Motörhead, "We Are the Road Crew"
• Kansas, "Carry On Wayward Son"

Three people to whom I'm passing this baton:
• SSG_Jas
• Complainr
• c3pomeara