lcoleman, I found this link from a person who appeared to have the same problem using a Vista machine, but he referred to the user image and logon screen so I'm not sure which he means. He fixed it by using a Resource Editor. The Resource Editor mentioned wouldn't save the edited file when I...
Have you looked in the oobe folder at C:\Windows\System32\oobe? There should be various PNG images at that location associated with Dell. Maybe you can change the image while keeping the same file name. Be careful though because PNG images may have several layers in them.
Gungistoker