[DanL]

Incubus is good for bass - Vitamin, Redifine, Certain Shade of Green. Battlestar Scralatchtica is also a good Incubus bass-song. Eve6 - On the Roof also has some bass and power behind it. AFI's Days of the Phoenix isn't very bassy, but strong bass would accent the drums and make it uber-awesome. Actually, speaking about drums, you could try Godsmack's (I think it's called) Voodoo. If I remember, that song is all bass practically. Oh, and who can forget Nirvana - Smells like Teen Spirit. Strong bass on that one would really make it sound great!

But something that you HAVE to try if you're looking for bass is the punk/ska cover of the Pink Panther Theme. The entire melody is the bassline. Add some punk to it, and it's gotta sound awesome on a 4.1 system.

Enjoy your system!

[edit]
Dah, how could I forget! The entire Blue Man Group - Audio album. Man, that album is nothing BUT bass-full drumming and it's all awesome. You could try downloading Blue Man Group - Drumbone, but I'd recomend you go for the entire album.
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