Some more cents to add...

You can stream Internet radio to the Squeezebox (SB) without the PC being on. To stream your CD collection, the PC must be on with Slimserver (the software that supports SB) running. If your sound system and computer on are different floors, and you don't like the idea of running around the house to power up your system, no worries... you can configure the SB to "wake" your computer and turn on Slimserver when you power on the SB.

Regarding gonk's points, the SB is very easy to set up and is basically a plug and play unit. I know very little about computers, and it took me no time to get things up and running. Another bonus of the SB is that it handles lossless formats like FLAC and has a pretty respectable onboard DAC.