I'm pretty sure that is because you're connected via USB. You can't 'migrate' the OS to, and boot from, a USB drive.
I don't exactly have the option to connect the SSD directly via SATA to the motherboard without replacing the HDD inside. Would you say that mirroring the HDD onto the SSD would be a better option? I do have the tools available to perform said task.
EDIT: Nevermind. I'll download a Windows 7 Professional 32-bit install disk and install it with the key I still have.