This. If you wallet was stolen the fact that you didn't do it immediately likely means the coins are already gone but anytime a wallet is compromised one should immediately transfers full value to a new wallet (preferably one on another machine). Using a temporary online wallet like MtGox or strongcoin account is fine because speed is of the essence.
With 2+ copies of private keys existing it is simply a race of who gets a transaction into a block first. With a good thief you won't have a chance they will transfer full balance of wallet.dat to a new address in a matter of seconds. Maybe you got lucky and it was a "bad" thief.