Dude.. in like half the laptops, the hard drive is mounted upside-down anyway. So, if the hard drive can run upside-down, it's only the CDrom that potentially can't (since everything else is 0 moving parts). Now, the CDRom clicks into place on the CDRom drive.. so the CD isn't going anywhere when you turn the laptop.
Using the laptop upside down will not harm it.. Spinning it around violently while you're using it could harm the hard drive or CDrom. However, if the laptop is off, the hard drive is parked and so is the CDRom drive... so, you can even spin your laptop around violently until your heart's content as long as the laptop is off.
Most good laptops will even survive a fall off a table.