[sdiy] dissipator for power supply

[Linium]

Hello,

I am hesitating between 2 kind of thermal dissipator for a new power supply 
(powered by a 36VA 2*18V transformer block). It will be regulated at +/-15 V 
and the dissipator are for the regulator 7815/7915.

i have choice between 3.9°C/W wich i know is quite good (and big and $$) and 
another only 7.1°CW.

Would this second one be enough ? i have no clue. It is intented to power a 
good bunch of modules...

Linium