While I do not use Macrium myself, I will back up what WHS is saying.
I will also add this friendly info....
When it comes time to reinstall Windows 7 on the computer which I will probably do in a year or so
If you are saying this in regards to Windows has to be re-installed every 6 months to a year as was sometimes
the case with XP.
Win 7 does not fall anywhere near that category. In other words, unless you are planning to do it, just to have a clean install, for the sake of having a clean install,, then your ok. But Windows 7 is not XP.
If they sent you an upgrade disk, you can try to contact Microsoft and tell them you want a full retail install disk. But they might have sent you the disk you have based off the information that you gave them with the product ID, meaning didn't have a Full Retail Disk, or they messed up.
You might want to find out if it is an OEM Replacement Disk, or a Retail Replacement disk. Retail means you can install it on any PC, but only one at a time.
OEM means it is tied to that PC, when the system goes away, so does the Key.
But they are not obligated to replace your stolen from your car items.
So, you can only take what they are willing to give you.
However, you can use the Upgrade Media and Key to do a full install without the need of prior install media, Clean Install with a Upgrade Windows 7 Version
And then we will discuss stolen Key,
Yes, the person who stole the disk and key could cause your install to become not-genuine by installing and activating with that key.
If the stolen key becomes disabled, you will get a warning, and then you can use your new key to re-activate.
It is up to you if you want to wait till then, or use the new key now.