If you need it, yes. Obviously. If you need to do a fresh install of Windows with a new copy then you would need to download the ISO from Microsoft and put it on a DVD or flash drive to be used to install onto your HDD with the new board installed.
Sorry, I already tried looking around on google but couldn't seem to find the right thing. When I click on that link it says it is a windows 7 enterprise 90 day trial? Whenever I look for a windows 7 home premium download the links do not work.
Every version of WIndows without a key is a "trial" before it asks you to activate your copy. Enterprise and Ultimate should have all versions on the disc. Somebody correct me if I'm wrong.