I do maost everything in ASP. But I was wondering if there was a way to have dreamweaver create a seperate js file when it adds javascript to a page.

Not automatically - that I know of. But I often take the popup window, swap image, etc JS and put it into an external .js file.

DMX will see it in the external .js file (as long as you have referenced it) and not insert it again. I recommend do exactly what you are trying to do.