I can tell you the current official position on this as I just attended a Licensing event in Southfield last week before the XP launch:
- All open-license products (MOLP, Select and Enterprise) are downgradable (Office and Windows) to any "supported" version (which I believe means Off97 and WinNT4 WS).  Not only that, but you should be able to order the media for any of the versions from their WWF
- Microsoft has removed the "work at home" option (where you could buy it for the office and install it at home for "business use only"), and replaced it with an "exclusive use laptop" section where by if your company (IE MSU) buys you a desktop and a laptop for your "exclusive use" you can buy 1 license and put it on both
 
There are also lots of interesting nuances to the CAL license structure and per-processor licensing structure for server stuff.  If anyone needs help, I've got contact info for our rep.s both local and at corporate.

        Rob Neary
        Desktop Support Coordinator & Windows Administration, MCSE
        Department of Physics and Astronomy
        125 Physics/Astronomy Building
        EMail: [log in to unmask]   Office: x32986

-----Original Message-----
From: John Valenti [mailto:[log in to unmask]]
Sent: Tuesday, October 30, 2001 9:16 PM
To: [log in to unmask]
Subject: Exchange fixed & WinXP