Presumably your PC has a full size ATX mobo . . . not a BTX mobo (totally different board arrangement) or a mATX (smaller mobo). If so, the new mobo solves the BIOS issue.
An OEM copy of Win7 for $100 may be necessary - however, you could try to borrow a copy of Win7 and use your existing license key. Microsoft may allow you to do this (re-authorize) because you had to replace your mobo, and you are under no obligation to use the same old technology
Sorry, I have no idea what you can achieve - if anything - with a program like setFSB.