Motherboard change & windows 7 problem?

Maybe not. Windows 7 may crash if it can't locate enough drivers for the new board. If the board is oem (dell, hp, ect) then it won't work with a non dell or hp board. You can create some recovery disks specifically for your oem board if you buy another new or used oem board by the same manufacturer. If your old board still works, you may want to keep it or sell it first before ordering.

o1die is right. No guaranty that it will work. You only option, if you want to be sure, is to save all important data now. Have all of your important data saved before you do anything else. Then, if it works, great! But if it doesn't, and you end up having to buy another copy of Windows, then you'll still be ok. +

What's the purpose of the motherboard change? Are you keeping the same CPU and other pieces?

Is it an OEM version of Win7 or full retail? (did you install it yourself or did you buy the PC with Win7?)