My work laptop is a Panasonic CF-C2 toughbook and I love it. It makes no sound at all, ever. With its tough build and rubber strap below it, it's comfortable enough to swing around in one hand with no serious risk of accident. It also has a small internal battery in addition to its detachable one. I don't have an extra battery to really make use of it, but the point is that you can hot-swap the battery while the computer is running.