I recommend that you do NOT go with the best card on the market... unless you have a huge amount of money to waste... in which case it would be better that you send the excess my way.
You can get a card that costs 1/2 to 1/3 as much, and still does everything necessary to run today's high end games as well as tomorrow's. You do not need to spend an arm and a leg to buy hardware that will cost half as much in a month... the differences between the high end and medium end graphics cards are rather negligible at this point in time...