Just in case anyone was as stuck as i was today trying to virtually load an ISO image. the Virtual CD Control Panel thing doesn't work in Vista, and for some reason VirtualCloneDrive wouldn't work for me either.
i eventually found a free tool called
PowerISO which works great. you can create several virtual drives and mount an ISO in each one. i'm currently installing Orcas Beta 1 from an ISO mounted across the network, i wasn't sure if it could do that but it had no problems.