Nope, once they're there, they're there. In fact, even when they are closed, they continue to report for 10 more years.
Right now, they are probably starting to help more than hurt. Oddly enough, in the American system of credit scoring, the more credit you have (while very little of it being used), the better off you are.
Your best bet is to sock-drawer the cards, pulling each one out every 3 or 4 months and buying a Slurpee or a Wall Street Journal or tank of gas, paying the balance off the moment it hits your online account, and putting the card away again.
The exceptions would be if there are fees for the cards or there is a problem with self-control leading to running up balances. In those instances, you might do better to close them. Just realize that if you do so, your total credit limits will be reduced, and your util (balances owed divided by total credit) might increase.
Check this thread by fused:
Clsoing Credit Cards
* Credit is a wonderful servant, but a terrible master. * Who's the boss --you or your credit?
FICO's: EQ 781 - TU 793 - EX 779 (from PSECU) - Done credit hunting; having fun with credit gardening. - EQ 590 on 5/14/2007