Webshots Equivalent ?

Hi All,
Can someone suggest a background desktop automated picture changer similar to webshots that you can have your personal photos
included which will rotate your desktop background in a time format of your choosing ?

My workplace has firewall blocked webshots as network traffic determined
that it called home to frequently..

Thanks.
TF
p.s. preferably free from adware, etc...

Google-> "desktop picture changer" and see all the results.