That's good news. My understanding of the licencing is that if it is OEM it is tied to the motherboard not the disk. Others will correct me if I am wrong.

System restore often refuses to work. I found I needed to disable my AV (Norton 360) before it would complete correctly. I now no longer use system restore and have turned it off.

The paid version of MR has a feature called Fast Delta Restore which can restore from a recent image almost as fast as System Restore.