turn on tex-pdf-mode when it's a beamer

Hi,

I have emacs 21.4.1 with beamer.el and auctex on ubuntu 6.04. It seems
like beamer.el does not turn on the TeX-pdf-mode automatically when the
document class is beamer (even after parsing it as such). I saw here[1]
some code that seems relevant, but have no idea how to use it (I have
next to no experience with emacs).

This[2] seemed relevant too, but it disables beamer.el...

I'd be glad if anyone can help me (please cc me: mehmetaergun at gmail.com

Thanks a lot,
Mehmet.

[1] http://www.mail-archive.com/auctex <at> gnu.org/msg01695.html

[2] http://osdir.com/ml/tex.latex.beamer.general/2006-01/msg00013.html