looking for a wallpaper program

[Meractik]

preferibly every 3 hours or at least everytime the machines rebooted a new wallpaper is selected, i have a huge selection of wallpapers inside one directory and just want the desktop to cycle them randomly. any suggestions on a program to do this?

 

[zerocool1]

webshots

 

[Meractik]

I thought webshots had spyware and stuff packaged with it, is it free?