Check for user group when accesing a page?

Hi! I’m trying to prevent subscriber users from going into <blog>/wp-admin/ and accesing to the dashboard. Just for aesthetics.

So, I’m thinking about adding a couple of code-lines to wp-admin/index.php, but I don’t know the functions or code for such.

I know how it should go, though. Maybe someone could translate it into WP 2.6.1 compilant PHP? Thank you so much!

IF (<user = subscriber>) {
<redirect to <blog> >;}

That would work, doesn’t it? How would that be in PHP? Tanks again!