I've been toying with using VNC to control my jukebox on a PC on the network, from my laptop...
This works, but is far from ideal!

On searching, I found there's plentyful software out there to control iTunes on a Mac, but nothing that I could see for Windows. Is there any such software out there, or anything similar for another audio player?

Also came across AirTunes, something like that would be ideal, if only the hardware wasn't necessary and a client could be run on a PC instead!

I seem to recall seeing something about a remote web interface for foobar.

Jreceiver has a web interface..

Giantdisc can be remotely controlled from a Palm. Maybe it can go from a laptop.

Check out the Foobar forums. I recall seeing components allowing remote controlling.