Maybe don't just forget about XM and Sirius, but you should consider forgetting about them while you're at work or at your home computer. http://www.last.fm/ is going to be your next music best-buddy.

Create a Last.fm profile and download the software to get personalised radio whose playlist is based on YOUR music taste. The radio player will learn what you listen to and start to stream music that you will love. It tracks the music you play in iTunes and Media Player and tells your profile. It learns you and exposes you to things that will make you happy. The more time you spend with it the more it will make you happy. Sort of like a niece or nephew (and you can shut it off, much like you can send your sibling's kin back to them). It streams the music too, so you can listen at work.

UPSIDE: It's free!! You can stream from all of your favorite, popular artists.
DOWNSIDE: You can't download the tracks unless the artist offers the tracks for free.

Site: www.Last.fm