Problem with photoshop and Raw files

Hello,
i bought the Canon EOS 5D mark 2 and i also have the CS4 photoshop.
this photoshop able to read any RAW files that i have from the past (that i took with a different camera of Canon- the EOS 5D) but can't read the RAW files from my new camere.
people told me to download a "RAW plug in" for photoshop but it didn't help!!
what do i need to download so i'll read the file?
please??
thank you all
Liat
you can answer me at my E.mail : leeaatel@gmail.com