Preinstalling the OS and putting some backup mechanism on a hidden partition of the HDD is the cheapest license, a PC manufacturer can buy from MS. We've read already, that the user can create one set of recovery CD or DVD. Great, if cheap media was used :Z
I remember, 10 years ago, there was a german PC manufacturer, who also sold their systems with windows preinstalled. Also, there was a recovery software installed, that allowed to create one set of floppy discs. Great experience if disc #39 of 50 was bad :Z
better yet (this happened to me) what happens when you want to upgrade your harddrive, but don't have an OS disc to install windows onto the newer, bigger hard drive? I called HP and asked them that, and they said "keep the factory installed drive as your system drive and installed the new drive as slave"
I have surfed HP website a couple of weeks ago, and I found some instructions concerning that issue. Also a set of recovery media was offered to buy, but I didn't remember the price.
So, I won't buy any brand computer, that comes with Windows preinstalled.