ummm...depends on how many fans you have. my personally i have 2x 250mm fans as intakes and a 3 fans as exhaust 1 180mm fan and 2x 120mm for my radiator.
theres nothing scientific about my advice because its just opinion. i would install all of them as intake and one near your cpu heat sink so that the heat from your cpu doesnt blow back into your case...thats all >.> most vid cards these days have exhaust vents anyway and if theres to much intake air and not enough exhaust...then the extra air will just go out the vents no biggie =)
zipzoomflyhigh's advice seems sound, however, what exactly are you planning on using that case for? If you're trying to cool any components newer than 5 years old or newer then you might want to think about upgrading to a case with larger fans.
The first case for my 5 year old pc had 5x 80mm fans and that wasn't enough for an old single core amd64 3500+/7800gtx combo. I upgraded to a case with 120mm's and the temps are much better. Just some food for thought.
arterius2, I do think that is a bit uncalled for... even if his question is last decade.