According to the EULA, no. A single user CD means one computer and is a license to have it installed on a single machine.
In reality, yes, however this counts as piracy I believe and should not be discussed on these forums.
EDIT: Unless it is the CD that came with your MacBook; that might have specific drivers etc for the MacBook not compatible with the iMac, (meaning in reality it still wouldn't work). If someone can clarify this it'd be appreciated.