I found some nice simple utilities to change the logon screen in Windows 7.  This used to require registry hacks, etc., but Microsoft built the capability into Win 7.  Will be useful for creating custom looks with company logos, etc.  The one caution is that the image must be less than 246kb or 256kb due to an MS built-in limit.  (Various sites say 246 or 256. Possibly 246 was a typo that others copied.)

http://www.thoosje.com/windows-7-logon-screen-editor.html
http://tweaks.com/software/tweakslogon/

Here's the registry hack: http://www.techspot.com/guides/224-change-logon-screen-windows7/

Thoosje also has some free logon artwork.