“I would buy my g/f anything she wants :) (within the 500 range)”

“One of my favorite purchases I've made from Apple is my AirportExpress.

The Express is plugged into my home-theater in my living room and I've got some really nice speakers upstairs in my office. So, using my iPhone and the Remote application, I can stream music to both my office (and by extension, the whole upstairs) and my living room. Having music playing in the whole house is great.

You can even use an AppleTV to be an 'AirTunes' client.

So, I recommend picking up an iPod Touch (if you don't want an iPhone) and an Airport Express base station (or two). (If you use WDS it will also extend your wireless network and operate as a network bridge).

See this blog post about it from Lifehacker: http://lifehacker.com/400235/turn-your-iphone-or-ipod-touch-into-a-multi+room-wireless-music-remote”