You will need to have your wallet connected to the internet in order to transfer funds to it. The safest way I can think of at the moment is to have a separate machine preferably running Linux and having a switch on it that allows your to give it Internet or not. I would turn on the switch when sending money to the wallet and than turn it off once the transfer is done.
You'd have to be connected to send *from* it. But to send to it? Nope.
Also, you can use blockexplorer to check what the block chain thinks your account balance is. Should be an easy way to check your balance while keeping your wallet "virgin".