you could export the keys and then import them into your other client, and then run bitcoin with the -rescan option. This is not for the feint of heart though. If you really want to do this, download db_dump and db_load (e.g. quick google search is
here), then db_dump your wallet.dat from both, splice the lines containing the keys (hint: they start with 036b657941 then the public key, then the private key on the following line) then db_load it back in. But probably easier to just transfer the money between the wallets
Will