I recently bought a macbook. Today I backed up the data from the old windows laptop I had been using and reformatted it.
I don't have a desktop pc anymore either. When I did, it was connected to my mini hifi so I could pump out tunes or watch divx with decent sound.
The mac book has lots of multimedia apps built in and I have music on it too, but its a chore to take it over to a decent sound system to get music going. Besides when its plugged to that, its not in a comfy location to browse the net etc.
So now the old lappy sits ontop of my set top box, plugged into the 5.1 srn sound beside the TV, playing music. I use Remote Desktop to control Winamp from my Mac.
The wifi is a little flaky either because of its position in the house or just that its getting too old and crappy, so I took out the wireless G card and put in a slower B card which seems top 'drop out' less.
I know its not that innovative, and probably overkill to dedicate a laptop to just playing mp3s but hey, at least its being used now for *something.
What have you guys done with your old computers?