How to redeem a private key in case it is compromised
If you want to redeem all funds from a private key and never use it again - you can for example create a new wallet file, run a bitcoin client, import the private key, let the client fully synchronise, and then send all your available funds to another address you own. After that, you can move your old wallet back where it belongs and use the new funds transferred. The redeemed key will not interfere with your normal wallet and you will have your funds.