Is WPF installed by default in all versions of Windows 7? Do all versions work with this? Not every machine comes with Pro or Ultimate.
As an alternative, try this (I believe this was profiled on T/R and ZDnet):
Win7 Logon Screen Changer
FREEware
http://tweaks.com/software/tweakslogon/The Tweaks.com Logon Changer for Windows 7 provides an easy way to customize the logon screen background with just a few clicks. Simply download the free application, run it and click Change Logon Screen. Using a feature that was originally designed for OEM computer manufactures like Dell and others to brand their computers, everyone can now safely customize their Windows 7 logon screen background. The actual process requires creating some registry keys, folders and files. To simplify the process the author created a free utility called the Tweaks.com Logon Changer that will allow you change the logon screen background with just a few clicks. The application will prompt for the location of the new background image and then install the new screen behind the scenes. Tweaks.com Logon Changer will even provide a preview of your new background on a logon screen. When you have settled on a good logon background, click the Test button to see it in action.
