I suggest using OWC. Google that for the link (on phone, can't post it)
They are one of the highest rated sellers for mac stuff.
Their prices are great too, significantly cheaper then canadaram. For example last I checked owc had a 8gb ram kit for a mbp for 250 while canadaram is 400.
They are a great company with great support - have used em a few times. They also show compatability charts for each product.
Edit. Looks like its
www.macsales.com