You can't really "update" a motherboard, as every one has a specific version that is tied to the hardware on the board. For example, if you have a Gigabyte v1.0 and you notice they are selling a v1.1, you can't update yours to turn it into a v1.1.
You can "replace" a motherboard -- but that is a complicated process and will most likely require reinstalling Win7, all your apps, and recovering all your data -- not something I recommend if you don't know how to do it.
Your system specs are empty of any hardware info, so we don't know what motherboard you're using that is "not supported". At least make, model, and version information would help.
Additionally, motherboards come in lots of different processor versions, so you would most likely have to purchase a new processor along with the motherboard. Also, memory hardware characteristics have changed over the years, so (for example) if you have an older motherboard, it's very likely the memory sticks are incompatible with anything new, so you would have to buy new memory.
And finally, depending on what add-on cards you have in your present PC, and the new motherboard "slots", you may have to either replace all the cards with new cards that are compatible with the new motherboard, or if you get a high-end motherboard (one that comes with onboard video, audio, and networking), you might have to switch over to using all on-board devices.
Have no idea what you mean by "a file .exe in Windows"! Are you asking if such an "update" can be accomplished by running a Windows app? Because if you are, the answer is no.