>Do you know where this is documented? or is it not?

See Readme.htm on VFP8 installation CD:

Operating System: Developing applications with Visual FoxPro 8.0 is only supported on Microsoft Windows 2000 Service Pack 2 and later, and Windows XP. You can create and distribute run-time applications for Windows 98, Windows Me, Windows 2000 Service Pack 2 or later, and Windows XP.