Call of Duty World at War is a great game. If you're getting the new one for free, this is worth a buy if you're a WW2 fan.
Assassins Creed 2 is a great game.
Madden 2010 is a must buy for all NFL fans.
NCAA Football 2010 is another must buy for NCAA fans.
Haven't played Tiger Woods 2010 so can't really help you here. But I do like the Tiger Woods series.
If you had to go with 2, I'd probably pick Madden 10 and Assassins Creed 2, since you're going to have the new COD anyways.