Nice tip man, I've always wondered about that.
As for converting, this is a freebie off of sourceforge. Pic the type of file the pictures are (BMP), the type you want to convert to, and direct it to the folder they are stored in. You can also have it deleted the originals after the process is done.
Couldn't get much easier
[You must be logged in to view images. Log in or Register.]
http://sourceforge.net/projects/bulkimageconver/