The main reason I'm hearing here is that the whole page doesn't need to be reloaded when one frame is changed. I can kind of see that. Can anyone offer me arguments to meet that? But the site is bizarre. The company logo has its own frame- no kidding!
uh changing a website that some one else designed POORLY blows! You can accomplish much the same effect with tables and its quicker. Nested tables are kinda crappy too but better than frames IMO. Just re-design it and show them the improvment.