see -
http://www.lotus.com/dominodoc
So... It supports, Windows Server 2003, Windows NT Server 4, and Windows 2000 Advanced Server, but not Windows 2000 standard server? Huh?
Microsoft Windows® Server 2003 Lotus Domino 5.0.12, 6.03, 6.5 and 6.51
Microsoft Windows NT® Server Lotus Domino 5.0.12, 6.03, 6.5 and 6.51
Microsoft Windows® 2000 Advanced Server Lotus Domino 5.0.12, 6.03, 6.5 and 6.51