The short answer to your questions is yes.
You need to purchase a new copy of the install media (Retail Full Version) of the Windows 7 64bit version you want (Premium, Professional, Ultimate) and perform a custom clean install. Save yourself some headache and don't try it with Upgrade media, although there is some discussion as to whether or not you can perform a clean install from upgrade media, I don't think overall the potential problems outweigh the price differential.
Also be sure to backup all your critical data files to an external medium for safe keeping.