Another thing... I have heard on Notebookforums that the license on the bottom of the laptop isn't a license for a full version of Windows, but rather just a license for the "restore" the OEM has set up.
So downloading an ISO of the retail or equivalent, you could be treading water with Microsoft.
But a lot of people don't care about that anyway.
I got one of the lucky few Dell laptops that still had the "Create Windows CD" program, which made me a plain XP Home CD without all the Dell BS.