If the wallet has been stolen and not yet spent then they have your private keys and the next 100 pre-generated keys your client was planning to use.

You need to move everything to another entirely separate wallet, ASAP.  Then back up the compromised wallet and make a new one from scratch..

You should keep the old wallet in case somebody ever sends something to an old address and you want to retrieve it - before somebody else does.  Just make Damn Sure(TM) you don't reuse any of its addresses.