Microsoft Licenses only!Licenses are for Organizations with many computers so they can save money by buying one CD(Media) and as many licenses they want for each computers so they can stay compliant.To qualify for license you need to purchase minimum of (5)Microsoft Licenses.This is another way of savings that we passed along our clients and customers. Operating system : Windows® 98, Windows® Me Millennium Edition, Windows® NT V4.0, Windows® 2000, Windows® 2000 Professional Minimum memory requirements : 32MB for Windows 98, 40MB for Windows ME and NT, 70MB for Windows 2000 Recommended memory requirements : 128MB with Windows 2000 Professional Minimum disk space requirements : 245MB