On my PC, I've just got a set of Creative Inspire 5.1 speakers, and they're pretty damn alright. Also connected (and able to be used at the flick of a crossfader) are my home made towers of destruction.

1x Kenwood tweeters, 2x mid range (also kenwood) and 1x 8 inch subby (no branders) in each tower, soon to be fitted with their own amps. When I get rich, that is.