I would actually reccomend getting Monoprice's Mini-Displayport to DVI cable, and a DVI to HDMI cable. This is what I did and it saved me from buying two adapters. I can now hook my MBP up to an HDMI port, or up to an external DVI monitor. Hope this helps.
P.S. don't buy the adapter from apple, it's exorbitantly overpriced.