With the old MB installed go to device manager and uninstall everything that can be uninstalled - video, sound, lan, USB, AGP, PCI drivers, IDE, etc.
Then put in the new MB. This will give you the best chance of a toruble free change over.
Best chance of succcess is if the MBs use the same chipsets. Next if they are the same chipset brand (SIS, VIA, NF, etc.). Least chance of success is if they are different brands.
Worst that will happen is the new MB will not load windows after the swap. Then do a clean install. More likely is that the system might be sluggish. If it is, uninstall and reinstall the devices again. if that fails clean install.
You can do a repair install which will leave much of your data intact but still wipe out all your programs and liscences.
PS Cheap ECS is redundant. But they are all I buy.