Birdy is spot on - so make sure you keep a backup of your wallet.dat file so that you will have the private key(s) for that address.
You can always send everything from the qt client to blockchain.info to consolidate it.
Is there a proper way to do that? I started blockchain.info by importing wallet.dat to here:
https://blockchain.info/wallet/import-walletDoes this method of importing not get all of the keys?