editting contextual menu with regedit?

Hi, I've forgotten how to edit the right-click contextual menu, using regedit. Advice please. Details: right mouse click on start menu. There are now too many items there & I want to reduce to a bare 3-5. Examples: "scan with AVG Free" and "agent ransack... ". "Find" in regedit did not bring these phrases up, typed as you see them, though in past installs it had. OS is wXPproSP2. I did do a search here in the BBS for a similar question, didn't see answer. Thanks.