Case&Airflow ???

This is for those case and cooling experts here

Heres the situation:

I recently acquired a Digital proris mx6200 case which i decided to modify for a standard ATX mobo. It took a bit of sawing and soldring to make an ATX motherboard to fit properly. The case is almost finished, just a bit of finishg up left to do. The only thing that bothers me is the airflow, because of the little holes in the back of the case (see the picture). The two 12v fans in the front are quite large about 14-16cm and should provide enough air to cool the insides of the case.
Normally the airflow in case should be done that cold air is taken from the bottom and exhausted from the top either by an external fan or by pwrsources fan but in this case the option of exchausting hot air from the top is quite hard to implement cause there is only a small opening between the pwrsource+Bay2 and the lower part of the case.
Now the question is should i seal shut the small holes and leave a small opening+another fan exhausting near the top beside the kb and mouse connectors or should i leave the cases holes open?


The pic should give a better view of the situation (although the proportions are not quite accurate).

Any comments?
-Lude-

Your air flow will be going directly out the back but any heat rising above where the fans are blowing air (heat from the CPU or Memory) will still need a place to escape to.
If you're not squeemish about cutting new holes...
One option would be to purchase a cheap slot cooler that's normally used for cooling video cards, then place it in the upper area of your case. It could vent some some air out of either side of the case if you cut a small hole for it.

If you don't want to cut holes you could buy a case circulator fan.

The key here is to have an unbroken airstream of fresh intake air across any component that may need it. No reason to cut a blowhole if you don't need one -with lotsa fans, hot air HAS NO CHANCE to rise and accumulate at the top of your casing. Your current setup looks fine to me. The two intake fans at the front blowing towards the mobo and the PSU as well having as the tiny holes behind for exhausting the heated air. Seal off other holes at the side, top, or bottom. Think of your case as one big ductwork.

Alternatively you can choose to bring the air directly to the CPU, by cutting a hole in the side panel just above your chip and putting a 120mm -very effective. The other fans will be either redundant or can serve as spot cooling for any stagnant areas like the stacks of drives. PSU blows out no matter what.