The cheapest option is a download and that will not run on a blank system. will NEED the backup DVD to perform a fresh install. I got this deal, It is very useful.
You can use it for a fresh install but its tricky. You are meant to install a different OS first and the license for the previous install is stored by MS.
To remain legal, you should run the uprage on a system already running an OS. If you have an old XP license you are not using, install that first.
There is a way of running a fresh install from the DVD but I do not believe it will activate properly. In the first instance, to conform to the EULA, you need an OS.