Remotely renaming a domained Win 7 computer
Solution 1:
I've always used the netdom renamecomputer method to do exactly what you are trying to do. On Windows Vista and 7, I encounter the same "access denied" error you do. You can work around this, though, by using the UserD and PasswordD switches:
netdom renamecomputer W7Img3-RPT49VA /newname:W7-clone-42 /UserD:DOMAIN\username /PasswordD:*
This will prompt you for your password, and then it will work without the "access denied" error. I imagine it has to do with the elevated token, but I am not sure.