Did you backup the Win7 Home to another HDD, or do you have the disk?. If so, just backup any data you want, then re-image/install Home premium to it. If you haven't got either, you will have to contact Microsoft/Laptop manufacturer for another copy of Windows to install on the same product key (should be fine since its the same mobo).
As for the Win 7 Ultimate on the desktop, your best off with a fresh install. Since the Ultimate isn't OEM there shouldn't be a problem with installing it.