OEM Deployment - Is This Possible?

Hi,

We are planing on deploying 40 Windows 7 workstations. These machines have been purchased with Windows 7 OEM pre-installed. Will it be possible to remove the current OEM pre-installation, create a new image using the MS deployment kit and then deploy this 'master' onto these machines? We don't want the same license key on each of these machines as this will probably be illegal and we would prefer to be on the right side of licensing here. Is there a single key (without upgrading to SA) that we could get from MS for this purpose (here's hoping :-) ),  so any feedback or suggestions would be great. :-)

Thanks,

Glenn