If my knowledge is correct, yes that is the version you want to get if your building a new computer. The upgrade version would be if you already had say, Windows Vista, on the computer and you wanted to upgrade to Windows 7. The system building version I believe is the OEM version of 7, which is cheaper than buying a retail version. You will get just the disk and a product key, no other documentation. The difference I between OEM and retail is that when you get a OEM version, once you use it on a machine it will be licensed to that machine and not transferable to another machine, but I someone correct me if I'm wrong on that.
Edit: Here's a link to a question of microsofts website about the difference between the two.
How exactly does Windows 7 Retail vs OEM - Microsoft Answers