We've got one. No idea if it will work, but the twin forums I've been on say that they can't live without them. One swings while you concentrate on the other... feeding, bathing, etc.
We went for this one...
http://www.mamasandpapas.co.uk/produ...4705028&type=I cos we liked the idea of the lights and also being able to plug in your MP3 player so you're not stuck with the same annoying tune over and over. They do seem to respond to Firestarter by the Prodigy though

which isn't quite what I had in mind!
Thankfully, there is an M & P factory shop near us so we got it for £30 less than the price on there.