IE 6 no longer supports .TIFs ?/!

We are working on an Intranet project which creates .TIF images and inserts them into webpages automatically. The system works with the IE 5.5 browser but does not work in IE 6.
It appears that the plugin that IE used to package is no longer included. BUT there is no mention of it on Technet or Knowledge Base. Can anyone confirm or deny this?
We are not married to the .TIF format (it is what the 3rd party provides us) but we would need some type of software that would convert the images to something web friendly (JPG / GIF). It would also have to convert the in batches automatically.
Any ideas would be appreciated. Thanks