Some years ago i did what i now call LDP (Linux Desktop Playing) with jack-rack, ardour, audacity, PD, chuck, python and even audacious. That was a really big mess,
You might want to look into wmctrl. that's a (linux) program that can interact with your window manager. Normally you'd use it to add functionality you are missing, but it could be used for a lot more. It's commandline-based so it could be remotely controlled, for example from ChucK or python. That way you wouldn't need to manually move your cow but the cow (ok, the cow's window) could hop around to the music according to some rules you could write on stage. Please note that I can't take responsiblity from lost income, audience, computers or sanity that might result from following my sugestions. :-p Kas.