Manually remove from right-click context menu

I had InfraRecorder installed locally, and it added "Burn with InfraRecorder" and "Burn with ExpressBurn" to the right-click context menu. I decided I liked ImgBurn better and got rid of InfraRecorder. However, these items are still in the context menu and if I click on them, it just brings up the generic "Choose program to open file with" dialog. Any ideas how to get rid of them manually? Are they stored in the registry somewhere? I'm on Vista x64 (which makes it tricky, with there being separate 32 and 64-bit registry nodes, but if someone can find it on a 32-bit system I can probably find it on 64...).