Unless you can get the EXACT same board, you're likely going to have to reinstall Windows.
If you can get almost the same board, you MIGHT be able to get away with only having to reactivate the current install of Windows.
I dunno about the Acer, but some manufacturer's cases even have proprietary MOBO connectors. (uhhhh ... freakin' Dell!)
In which case you probably wouldn't be able to use a different brand board in the same case.