Thanks. That really is simple (and beautiful)!
I wonder though, isn't it hard for your wrist after a while when you can't rest your lower arm on the desk?
I have a MBP; I rest my wrists on the huge slabs under the keyboard which works absolutely fine. If you computer doesn't have that, then yes, I would make a real table on the table so I can rest my wrists.
When i'm writing stuff I'm usually replacing the laptop by a writing pad.