With Win7 it's up to you, generally you don't need a clean install, will want Win7 up to date, make a backup of your data , then simply install the HD in your new build, generall scenario will be it will boot and Win will examine all the new hardware and install drivers for all and you will be up and running... next you install all the latest divers for the new mobo from the mobos website, next step is to run a good registry cleaner (Wise has a good free one) to clear out references to the old junk from your old mobo....then Win will prob let you know you need to re-activate, do it online - will normally get an error notice and phone number, it will have you input the erro, then ask how many computers you have it installed on, say one, then about 95% of the time they will issue a new re-activation code and you are good to go, have done this numerous times, on occasion even going from AMD to Intel