this is WC qualifying. each region does their qualifying differently. In Europe there are about 8 groups, the winner of each group gets in with a playoff amongst the second place teams for additional spots. In North America, there are currently 6 teams remaining, the play home and home with the top 3 teams getting into the WC and the 4th place team having a play in game with a low finisher from another region.
It would be a pretty big upset if either of these teams didn't qualify for WC10. Don't focus on the fact both teams are likely to qualify, any time you have competitive matches (i.e., not friendlies) in soccer the tension and intensity level is high. These two teams hate each other and the US has owned Mexico of late. If you appreciate tense, intense and hard fought sporting events, this is the game for you.
Kind of like LAL and Boston the other night or Duke/UNC, doesn't really mean a ton in the grand scheme as both teams will make the playoffs/tourney, but the rivalry and intensity is what makes the game. You really should tune in.