airflow questions

[Schadenfroh]

allright guys, say i get a case with 1 front 120mm fan and a rear 120mm fan and i have a PSU with 2 fans. should the one on the front and back be intake or should the one in the back be output? what is the best intake/out config for a system like i described?

 

[Xtreme2k2]

front one should be intake, and the back one should be exhaust, so the cool air blows in through the front, over your components, and out the back