Andrea, you are correct about Site5 our hosting provider allowing - in principle - near unlimited size of attachments.
However that being said, there *are* ramifications of allowing unlimited attachment size. If everybody should post 100 MB TIFs, server load *would* increase by leaps and bounds, and big images are a breeze to steal and use illegally later. Copyright will be severely threatened.
I think a balance point should be struck and most images (as jpg) might be seen pefectly on web pages and provide a lot of detail within a limit of 1 or 2 MB. I'm going to increase the upper limit for attachments to say 2 or 4 MB if/when the inline issue is sorted.