The UAC is due to a misunderstanding of how Vista security works. Even though you may be running as administrator the system is running you as a user and does a UAC prompt when it needs to elevate privileges. The entire Program Files folder is read only
to Users so if it writes anything it forces a privilege elevation. Stephen with his located in a different location that he has full rights to doesn't need elevation (thus no UAC).
The fix to this is to change the read/write permissions on either the file or the Terminal's folder in Program Files so your account has at minimum Write permissions. You could also set the Everyone user to have write permissions. This should clear up
that issue permanently. The other alternative is to install in a different location.