I have been playing around with a couple of things,
Found this and have tried a test project, works well with a flash file. Free for non commercial use.
http://www.tenmiles.com/screenswift/index.php
I also have been playing with a small project in C#, I haven't done too much graphics programming but it does promise to be more dynamic.. can dump graphics in a folder or download from a chiptalk directory.. Were as the flash is static once it is generated that's it.
a template project is available here.
http://www.codeproject.com/csharp/scrframework.asp
Visual Studio 2005 has a screen saver template, which can be used but it seems geared towards, RSS feeds. I can look into if this is desired functionality.