As Jennifer says, just uninstall Office from the old laptop.
Install from original disk and use the same License number.
When installed you will be asked to activate - over the internet or by phone - select over the internet, and you should be activated and good to go without using up any additional licenses.
I recently removed Office 2007 from my old PC and installed it on my new PC - using the original CD and the original license key. There were no problems - it activated OK and runs just fine.