WebSite Submissions Question

Hi All On the website I am building, my Index page (index.html) does a check to see if it is Internet Explorer or Netscape Navigator that the user has for a browser.. and redirects the user to either header("Location: ../nav/index.html"); or header("Location: ../ie/index.html"); depending on the result... I have one worry though, and that is how do search engines react to this, when ranking the site? I have all the meta data optimization etc after the redirection but do the search engines see this or follow the link?? Do they ignore the <? ...... ?> structure?? I already parse all .html through PHP with Apache, hence the .php is not required or penalized... Thanks for any advice... Daz --