No problem. It's always best to ask and make sure first than to just jump in and be sorry later.
I would manually backup (copy and paste) any files that you do not wish to lose first though. After you replace the motherboard, you are going to need to do a clean install
of Windows 7 since you cannot use the old installation on a new motherboard. After the clean install of Windows 7 and installing all your drivers, programs, and such, then create the system image backup.