In Window 7 You have to turn of UAC (User Access Control) or run "install.bat" as Administrator - right click on .bat or .reg file and select "Run as administrator".
To turn off UAC go to help, type in "User Access Control", select "Turn User Account Control on or off" and follow instructions.
When installing new full MapSource map with Setup.exe or .msi it is good thing to boot Windows 7 with option "Disable Driver Signature Enforcement" by pressing F8 on system boot, because MapSource installs drivers for Garmin devices and sometimes it becomes "Never ending story" on Windows 7 if this option is not selected (too many questions, long time between them and sometimes never ends).
You could use in MapSource maps generated from .img files, but do not transfer them back to .img files from MapSource, rather use original .img files. If needed to merge them with other maps use this guide:
[Only registered and activated users can see links. ]