I'm thinking of using a keep-in-frames script like:

if (parent.frames.length==0) window.location.replace("index.htm")

in our site to keep our navigation frames visible, even if the page requested is not a frameset.
This will work. However, I was wondering if such a script wouldn't be followed by browsers and searchengines alike, thus effecting the searchengine ranking.
Do spiders still 'read' the content of the original page, or are they also redirected to the frameset? And if not, is there a way to get both the ranking and the frames?