If you also have MS Office installed on YOUR desktop with a valid licence, it may be acceptable to reuse YOUR product key on YOUR laptop, provided that you don't use both at once.
Please read the licence terms carefully.
You must use the same install disk on both machines.
Electro
November 2011
You can't. You'll have to buy one like everyone else.
T
October 2011
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix notebooks/laptop pcs.