All you need to do is right click on one of your pictures, and in the right click menu go to "Open With", then under it click on "Choose Default Program"
When that opens highlight the default program you want to use, such as the built in Windows picture and fax viewer, then at the bottom put a check on make this the default and then click ok.
That is one fast way to do it, the other way is to go to control panel and go to default programs and set the default there as well
Shane
