So I understand, you have 3 pages.
page 1 can look like this:
Page 2 (framed.html) will have a link that, when clicked, will replace Page 1 like this:
When the "changepage" link is clicked, page 1 should be replaced with page2.html. This works in IE 6 and Firefox 1.0, at the very least. All I have done is to set the target of the "framed" link to "_top".
Hopefully this helps.