Even with an upgrade version you can do a clean install.  When you boot the Windows 7 Upgrade DVD you are given two options; Upgrade or Custom.  Selecting Custom will allow you to format the drive and do a clean install.  That's exactly what I did.  Sorry don't know anything about the Upgrade Assistant from Dell.

larrens,

Thank you for contacting the Dell Community Forums.  The Windows 7 disc you received as part of your kit comes with an upgrade product key.  This key typically will not work unless you run the install from within a previous, compatible operating system, so if you tried to do a clean install from that disc onto a blank hard drive, you would probably get a message saying the key was invalid.  In the past, Microsoft allowed users to insert a previous OS CD to confirm that they had a qualifying operating system, but starting with Windows Vista they changed the process and now the option to confirm compliance by inserting a CD from a previous OS is no longer available.  You may want to take a look at this forum thread to see what your options are if you decide to try a clean install from upgrade media on a blank drive.

Yes that is correct, but like Chris' thread indicates an existing eligible OS must be present for the upgrade to continue.

see HERE. Follow the steps just substitute windows 7 for Vista. I did this on both of my systems so it works.

You can use it on a clean drive and you do not need a previous version Os

Thanks for the forum threda - so reading that it seems that as long as I do a "Custom install" from the Win7 DVD & format it through this process I will be ok & it will work?

Is my understanding here correct?