MagicWB will make your Workbench look like this, no matter if you register or not:
http://www.sasg.com/pic/mwb_preview.gifThe only difference between preview and full version is that every icon shows "demo version" when you click on it while in the full version all icons have two images.
MagicWB cannot be registered any more, it's out of business.
MUI is completely unrelated. It is only needed for programs using MUI. It does not do anything to Workbench. MUI can still be registered through the author.