Why won't windows 7 Enterprise upgrade, upgrade Vista Ultimate or Windows XP? while trying to upgrade Win Vista Ultimate it reaches a point where it says Win 7 cannot up grade Win Vista ultimate and I need to stop and restart and select new installation and will lose all programs installed, what is the point in having an upgrade version if it wont upgrade anything?

Normally you can only upgrade from one version of Windows to the same version of Windows, or from a basic version to a more feature rich version. You can for instance upgrade Windows Vista Business to Windows 7 Enterprise or Windows Vista Enterprise to Windows 7 Enterprise. You cannot do an in-place upgrade from any version of Windows XP to Windows 7 so in those scenarios you must do a clean installation.You can see all supported upgrade paths on http://technet.microsoft.com/en-us/library/dd772579(WS.10).aspx

You are merging different questions. Apart of the supported upgrade paths given by Stenis, you should be aware that Windows 7 Enterprise is, featurewise, the same as Windows 7 Ultimate. The only difference is that "Ultimate" is a retail SKU you can purchase for a single computer, whereas "Enterprise" is a system based on volume-licensing that you can typically purchase for >500 computers. So, an upgrade from an "Ultimate" to an "Enterprise" version is a somewhat strange idea. If you want to change the licensing model, you have to reinstall Windows from scratch. In addition, are you sure you have a "Windows 7 Enterprise upgrade" version? I can be wrong but that's the first time I heard about that."I think there is a world market for maybe five computers. (Thomas J. Watson, Sr.)