Resizing/changing multiple images at once

[meant]

I guess the title is a bit self explanatory. Heres my situation: I have about 50 jpeg images that are at a rather large resolution. Instead of going to each and everyone, resizing and saving it as a gif, is there a way to do the whole job at once? Thanks in advance.

[Tanel]

Paint.net is not appropriate program for this, use IrfanView instead.

See this batch conversion tutorial for example.