> I am using Librecad portable on Windows 7 64-bit.
It will be controlling file associations.
> I am only a user of my PC and I do not have Administrator rights.
Would you like to install on the computer as a user?
Trivial to [hack and] change installer from HKEY_LOCAL_MACHINE (HKLM) to HKEY_CURRENT_USER (HKCU) and recompile.