The license that windows comes with won't allow you to do that with out having to install the OS again. The reason why is that deep inside the Windows OS, it checks your engraved MAC address on your motherboard and compares it to the MAC address it has saved (in a file) from when you first installed it. If they don't match, it will think that you have an unofficial (or pirated) version and try to force you to buy the product. Good news, just reinstall with your disk (if it isn't OEM version, you should have three free installs on different motherboards) and it will save your data. Just be sure to go into advanced settings and tell it to install but keep the data on it.