I've tested this on my computers and got some interesting results. On my secondary XP computer the registry setting did work if I chose to create a new map based on the �??blank�?� map of �??My templates�?� , or if I opened previously created map projects. They opened with the classic snapping setting checked.
But if I instead opened a new map based on my normal.mxd (which does not have the box checked), they opened with the snapping setting unchecked, and any map I opened after it in that ongoing ArcMap session had the setting unchecked.
On my Windows 7/main computer, I had saved my normal.mxd with the classic snapping box checked and I don�??t yet have the registry tweak in place. Any new project based on the normal.mxd or any previously created project that I opened thereafter in a continuing ArcMap session had the setting checked. But if I started a new ArcMap session then maps based on the �??blank�?� template or previously created maps opened with the setting unchecked.