Never negotiated with a collection agency but if that is the case then it is just a simple expected value question.
The item will disappear from the credit report sometime in 2012.
So is two years worth it?
Depends on the amount of money involved, MrsRebel's need for credit in the next two years, and if she feels any moral obligation to pay?
If you are not going to get the item removed though I see no reason to pay a stat barred debt.
In fact if my understanding is correct it will actually hurt you since the date of last activity will reset and now the item will remain on the credit report until 2016. I'm not 100% sure of this but assuming my interpretation is correct this is a major design flaw in the current credit system that basically makes it retarded to pay any debt that is over 2-3 years old.