I'm looking for a way to play music from my PC on speakers over a wireless network. I've done some googling and I'm finding lots of stuff that is really expensive, has fancy LCD displays that show what song is playing, and all kinds of stuff that I don't need.

Here are my requirements:
- No USB transmitter attachments needed
- Just plays what would come out of the PC speaker (none of these systems that only play certain formats of music)
- No propriety software needed to stream audio (other than device drivers, etc.)
- Works on my wireless network
- I'll provide my own speakers
- Works with Windows (XP and Vista)

I'm hoping that I can find something pretty cheap since I just want something that only streams audio and doesn't need to have all the bells and whistles.

Any recommendations?