Can you make a backup and use it on another computer?

I might do a clean install of windows on my laptop soon because I found a rootkit on it a while back, hiding in the winsxs folder. It might still be there. So If I do a clean install then make a backup from my desktop can I back it up onto my laptop?

Yes, depending on what imaging program you use.

You will probably need something like paragon adaptive restore to allow windows to boot on different hardware.

You also need a windows product (license) key which allows you to move it to a different machine - or a separate product key altogether.