Are you sure your car is getting hot?
Even if the gauge reads high it might be somethin else. In my Civic (R.I.P.) there was a thermal sensor (I believe thats the name of it) under the distributor which threads into the head and is the signal for the temp gauge (wasnt even meant for my car - who knows who put it there). It read hot all the time and I was freakin out that my fan wasnt comin on when my car was just fine.
Basically, make sure something is wrong before you throw parts at it. Much more cost efficient in the long run.
Preeeeaaaach