Computer speaker conundrum: how can I play the music on my computer in multiple rooms?

All of my music is on my iMac, and I'd like to play it in the kitchen and dining room as well as the computer room. I've looked into wireless speakers and it sounds like they're pretty bad. So I'm resigned to threading wire around the house. Does anyone have experience doing this sort of thing? I'd rather not run the sound through a receiver, as space is pretty limited in my apartment. Any recommendations for speakers?

As a sub question: can I get better sound with speakers that run from a USB port, rather than the single-plug speaker jack?