vero - 3:44 am on Aug 21, 2008 (gmt 0)
jos - is your site on a hosted server? Some don't let you write your own 301 for this redirect. If that's the case, just contact your hosting company and ask them to do the redirect of index.html to /, then test it your self to make sure it was done correctly.
While you're at it, you might want to ask them to redirect non-www to www or vice versa, depending on which version you prefer - again to avoid duplicate issues.