as someone who has worked and run a small "mom n pop" store, i had several people ask "can i have windows not included on the system"
for awhile i was allowing it, however this is what happened.
for those that are not really computer literate, when they get the PC home, we usaully have to spend 2-3 hours walking htem through the install process.... constantly we would get calls asking "what is a driver??"
If htey brought their own legal copy of windows into the store, we could load it up with their older win95 or whatever, but alot of htem had burnt discs, which we wouldnt work iwth, or it was just hte uprade disk, and they couldnt undrestand why we wouldnt install it for htem. They didnt understand the differences between "update" and "full version".... caused alot of head aches for us.
we implemented a policy where if you install your OS yourself, we wont provide any phone support or tech support during that install...... well christ that pissed off alot of people. they would come back wanting a refund cuz the video cardwouldnt work.... thats cuz they installed the wrong drivers, and we would have to re do their system, god forbid they had any important data allready on the system...
hence, we implemented a policy that an OS HAS to be installed.
i heard that dell and the big oems pay 8 bucks per windows license