Windows 7 - Custom v Clean Install

As people begin receiving their copies of Win 7 upgrade, there seems to be a problem doing a clean install. My question, what is the downside of doing a custom install, with a upgrade disc and the resulting windows.old, rather than a clean install, on a formatted drive?

rich

Down side is system is in limbo. You never know if the system is using an old value imported from win.old or a new one. If old had problems you can import them.

ken

If i get this correctly...

Ideally a clean install will give you a fully functional OS and since the process formatted your system its supposed to be - well "CLEAN"

Whereas a Custom Install is done when you have data left on your old OS that you want to migrate to the new one. So its possible that old problems may still pop up co'z of the old files...