Kluczowa część
wywiadu:

MJF: Does Microsoft have downgrade rights for Windows XP planned as
part of Windows 7?

Microsoft spokesperson: Yes. This is not the first time that
Microsoft has offered downgrade rights to a version other than its immediate
predecessor and our volume-license customers can always downgrade to any
previous version of Windows.

(The spokesperson clarified later that downgrade rights allow users to
install previous versions of Windows, not just the most recent predecessor. In
other words, a volume-license user who wanted to downgrade from Vista could,
technically, go back to Windows 2000 or even Windows 95, not just XP. Who knew?)

Wynika z tego, że licencja Windows 7 będzie dopuszczała
downgrade Windows 7 do Windows XP oraz Windows Vista (co jest
oczywiste). Ostatnie zmiany volume-license umożliwiają również downgrade Windows
Vista do wersji wcześniejszych niż Windows XP.

Postaram się potwierdzić te informacje.

źródła:

Microsoft will allow Windows
7 users to downgrade to XP – ZDNet