Was... erm... that really necessary? 
Anywho, I do believe that the original was a system seller, but not in the flashy 3 week sales barrage that we see of many other titles.
Uncharted has sold 2,500,000 copies on the PS3. Being that it is a brand new IP, one would say that this game created a brand new audience for the system as well. An audience that has come to know and love Drake. Now, with the release of Uncharted 2, do you really think that this new game is going to create brand spankin' new audience of another million or so, ready to buy PS3's? Or will the audience that Uncharted 1 created come back to buy the sequel?
Sure, Uncharted 2 will create a larger audience, we're seeing it already here on VGChartz. But will it create anything substantial, like... boost PS3 sales to 300,000 on its launch week. I doubt it.