Carrying your computer in your hand can be cumbersome, use a computer bag instead. It only comes in one colour, black, but it does look quite neat.
From Ecprof
D31180 - SMARTSKIN LAPTOP SLEEVE 13.3IN
The product is available from £20.90 at international stores.
Technoworld PLC
Dicota Smart Skin 13-13.3
This product is also available at 3 unverified merchants.