Multi Language Site - PHP only

[hgtwn]

I am creating a multilanguage site and need some feedback from you all.  What I started creating is a site that uses the same page for each language but calls it's respective language file (ie. [b]en.php[/b]).  Depending on what language is selected (www.site.com/page.php?lang=en) the respective language file will be called by [b]include('/en.php');[/b]  Is this a good way to handle multiple languages?  I want to stay away from databases and this was my solution.  My concern is that I don't know how search engines like Google or Yahoo handle searching pages like this.  I want all of my languages to be included in the search but does Google search [b]www.site.com/index.php?lang=en[/b] and [b]www.site.com/index.php?lang=spanish[/b] separately?  I want to be able to search my Spanish terms and go to the right page with the right $lang var set.  Is this what happens?  Thanks for the response!