if you're just checking balances, you may want to look into moneromoo's advances in watch-only wallets. if you run help from simplewallet, you can save the wallet as a watch only wallet. So you can delete your old wallet files (the ones that can spend the XMR), and then load the watch-only wallet. That way, if your windows gets hacked, the only thing available is a view key wallet, so the hacker can't spend your money, only watch it trickle in.
note - you must then delete your original .keys file, then rename your .keys-watchonly file to a .keys file
you can then load yourwallet.bin again, and it'll pull the viewkey from the new keys file using your same password. So in order to protect your funds here, you'd just make sure your original keys file is long gone. One of them disk thrasher super delete programs would do.
In either case, the save_watch_only makes you create a new password. So, you'll need to use that instead of your original wallet password.