Hi, all first time here.

just wanted to know best place to put case fans, i have room for 2 at back and 2 at front. but i have 2 high speed fans and 2 normal cheap fans. (80mm) i also have a cas that can turn 2 fans on/off as i want should i make use of this

Place one 120mm fan on the rear as close to the cpu as allowed(since you have two locations) and place an 80mm fan on the front. You should always make sure your exhaust fan can draw out more air than your intake fan can to create a negative pressure inside the case. But don't overkill by putting two 120s in the rear with only one 80 in the front.

ASUS P5GD1
P4 3.4 Socket775
ABIT RX600-SE V-Guru
1G Corsair PC400

the high speed fans are 80mm aswell.

is having one high speed and one low speed fan as exhaust at back of case and one low speed intake at front best?

or would you have 2 high speed at back, and 2 low speed at front?

also what is a good pcu tem, max?
and case temp?

Thanks