When to release an object in VBScript (WARNING newbie question) :)

Hi,
Newbie question here. What situations do you need to be sure to release an object. I am working with a QTP (HP Quick Test Professional) script that uses VBScript. I was wondering if I have a small script that runs in a for loop should I do this because of memory issues? can NOT setting an object to equal Nothing cause memory leakage or slow performance OR...something else(?). Hope this is not too dumb a question.
 
Thanks,
George