I assume you're using Winamp to play your mp3 files back?
If so, visit
www.winamp.com and have a look in the Plugins/addons section for Winamp.
There are few 'remote' UI interfaces to Winamp, not sure about remote queueing which is what you are really trying to achieve.
Now, if you're not using Winamp, other than using winvnc I don't know of anything that will do what you want.
Of course I'm probably wrong and someone has written a Explorer (right Click menu) addin that lets you "send" a "play remote mp3 file" message across the network to your other PC.