Yes you will have to reinstall windows, I could go into the complex reasons why, but i don't think you'd care to know. Also, with a new motherboard make sure that the board-size (atx, micro atx, etc.) fits your case, the last thing you want to do is have a spiffy new board and processor with no case to support it. Make sure you mount your spacers on the back of the board so there is some seperation between the board and the case. Make sure the new CPU your mounting has the corner in the right part of the socket, you can check the motherboard guide for clarity on this. But then you just plug everything else in and it'll work, you'll just need to redo drivers.