Personally, I'm running a Topeak MTX TrunkBag DXP and I love it. It's a combo trunk bag and pannier, and it fits my laptop perfectly. Though it doesn't have padding in the pannier, you can get a padded laptop sleeve to take care of that.
http://www.topeak.com/2007/products/bags/bagsmain.php
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Everyone is entitled to an informed opinion.