Do Delegates Matter?

I understand that momentum is important in primaries and that winning gives you momentum. However, what actually counts at convention is how many delegates you have. McCain won New Hampshire, but only picked up 7 delegates. And now he's the front runner? Romney is actually the leader in delegates with 30, after coming in second in Iowa (12), first in Wyoming (8), second in NH (4) and his 6 Superdelegates. Huckabee is in second with 21. Michigan is really important for Romney, but the Republican race is much different than the Democrat race, which is essentially down to two candidates. The Republicans still have at least four with a realistic chance at the nomination (Romney, McCain, Giuliani, and Huckabee).
Romney has some strengths going into Michigan - it's his home state, his dad was a popular governor there. Michigan's economy is in the tank and Romney can point to his experience turning around companies, the Winter Olympics, and the economy of Massachusetts as Governor. As Governor he took a $3 billion deficit and left office with a surplus without raising taxes. Romney accomplished this by cutting spending and with various programs to stimulate the economy.