Firstly you need to
back up your wallet to a safe place on your HDD or flash drive.
DO NOT EDIT WALLET.DAT WITH A TEXTEDITORThen do the following:
1. Uninstall the client
2. Download the current version from
bitcoin.org3. Install it
4. Copy your backed up wallet to \Users\[your user name]\AppData\Roaming\Bitcoin\
5. Start the new client and wait until blockchain is up to date
You should see the correct balance.