@
Kovid -- if calibre creates Open With associations, I am thinking of the new code for Windows 8

, should those be removed by the uninstaller? They get
automatically created on calibre's launch IIRC.
@
leitz -- In general, if I want to remove a program under Windows, I would use
RevoUninstaller, which offers to delete any/selected registry keys and configuration data from wherever it finds it, system or user areas.
I have rarely seen the program that didn't leave
something where it shouldn't. This is less of a problem on Linux, where the package installer indexes every file an installation creates. Maybe Microsoft will finally do the same someday...