i want my computer back to factory settings after switching from vista home premium to windows 7.

I own a dell studio xps 435mt.  It came with windows vista home premium 64bit OS.  I've now uploaded windows 7 ultimate 64 bit os.  I would like to roll the computer back to the original factory settings and can't seem to figure out why.  I've read that i need to hit the f8 key and make my way to the dell factory image restore tab, but it's not there.  there is a pc restore program in my recovery drive.  However, i just get a error sign without detail every time i run it.  My THEORY is that if i reinstall vista using the original os disk provided by dell, then I should be able to acces the dell factory image restore program and return it back to factory settings.  I would like to go this route to avoid excess time and error.  the recovoery partition seems to be intact and holding all the information from the original settings.  If it transfered to windows 7, will it be safely there if i reinstall my old copy of vista?