Having had a quick play,
this keyboard from comfort software (you want "comfort on-screen keyboard lite") seems pretty good. It's not resizable, but there's a variety of different styles of keyboard available (right click on the top bar of the window to get the menu) and lots of options to play with.
The Lite version has a 30 day shareware trial, but after that it's a pay up product. Should give you more chance to find an alternative though. If there's nothing good out there already I might have to write one