Is there any logic behind paying closing costs or paying no closing costs?

Is there a magic formula to this?  The option is to have 0 closing costs with a higher rate or pay closing costs with a lower rate.  My math tells me to take the monthly difference in payment's, and then see how long it would take to pay that off to equal the amount of the closing costs I'm paying.

If I'm going to live in the house longer than that time, than it would be worthwhile to pay closing costs now?

Or is there a magical spread % that I should be looking at?