Did you make a backup of your wallet.dat file? . . .If not, make a backup now . . . and copy it to a safe place
+1
This is the most important step. As long as you have the original wallet.dat that has the private keys associated with the bitcoin addresses you are using, you'll be ok. If you lose this file and don't have your private keys written down or stored anywhere else, then you can kiss your coins good-bye. Be VERY careful and don't mess with anything unless/until you are sure that you have a good copy of the correct wallet.dat stored in a safe place.