Hi rwhaley, You might have an enterprise card in the R610 which need not have license like the new 12G R620. The only way that you can do through DRAC connection is to upgrade the express to enterprise. You can refer back to your Dell Sales rep, and request for a 30-day trial license, which might help you to install your OS.  
I have a fresh PowerEdge R620, 8 bay chassis, no optical drive, with iDRAC7 Express edition. I've got the DRAC web interfaced configured and I can access it just fine. I have an Ubuntu .iso image sitting on another server accessible via HTTP I want to mount and install from. What's the method to do this using DRAC7 Express? Is this not possible? I see the "Remote File Sharing" configuration settings but they're not available in the Express edition. The help docs say I need an Enterprise license in order to use it. I assume that's the only way to mount an ISO over the network, which is unfortunate because our old R610's didn't require an extra license just to mount network ISO files. Let's assume I can't mount an ISO image as virtual media. What's the Dell-recommended method to do an OS install with just DRAC Express and no internal optical drive?
OS install path for R620 and iDRAC Express