4/5 — solid OS, confusing OEM rules. Rating for today’s use: 0/5 — but a 5/5 for nostalgia and licensing archaeology.
The OEM Product ID on NT 4.0 represents an era of trust-based licensing. For a retro VM or offline historical exploration, an OEM key works fine. For business or internet use today — absolutely not. If you find a genuine sticker on an old Compaq DeskPro, treat it as a museum piece, not a production OS.
An OEM Product ID legally died with its original motherboard. If you upgraded the PC or replaced a failed motherboard, the OEM license was technically void. Reinstalling from an OEM NT 4.0 CD and using the sticker key was fine, but migrating that key to another machine broke the OEM agreement — though the OS itself never checked.
