Rendering .m1v files instead of .mpg files?

This question picks up on this thread:

http://www.moviecodec.com/thread/1143.html

That particular post was helpful, but it didnt specify much about what parameters to use in the advanced menu of the multiplexer.

The most frustrating thing about this is that it keeps saying Premier Pro 1.5 keeps saying it is going to save the file as an .mpg, and the first time I ran it - it actually did output an .mpg file. But after that it stopped, and now even though it says it is going to export a mpg file, I get an .m1v. Weird. The Help files says mpeg1 is the format to use for internet formats, and I set it there, but grrrrrr...

Heh... I love learning new apps...

TIA

Will