Big users are fretting that they won’t be able to buy Windows 3.1 after Chicago ships, US PC Week reports, adding that most personal computer manufacturers plan to pre-install Windows 4.0 as soon as it is available, adding that buyers will be able to get machines configured with Windows 3.1, but only as long as Microsoft Corp sells it; Microsoft plans to end retail sales of Windows 3.1 and Windows for Workgroups when Chicago ships, but the will continue to supply it on an OEM basis as long as people want it – Resellers will be able to fulfill requests for 3.1, said Rogers Weed, Chicago product manager, but customers will dictate its availability – it is likely to vanish from retailers’ shelves but customers will be able to order it.