Windows re-install after new mo-bo?

I am thinking about getting a new motherboard sometime in the future (either http://www.newegg.com/Product/Product.aspx?Item=N82E168... or http://www.newegg.com/Product/Product.aspx?Item=N82E168...) and i was wondering if i will need to re-install windows. I dont have a windows disk and i will not be changing the processor with it. All hardware at the time of the switch will be the same except for the change in motherboard. I will be upgrading from a m-atx dell board that i got on the cheap.