There is no "one format fits all" option. If you're screen shotting a dialogue box, .gif often works best because there are just a few colors without much anti-aliasing, which is what .gif does best. If you're posting the results of a render, .jpg is usually the way to go.

The best thing to do is to do print-screen and then paste it into your graphics program and do Save for Web. If you can't do that (my version of PS gets weird and sometimes refuses to read what's on the clipboard), then save it as .tif, then open it up in your image editor and Save for Web. You should be able to then look at the different file options and see both the quality of the image as well as the file size. I know that PS reports that info, and I'd assume other programs do as well.

Message edited on: 01/15/2005 21:08