From the MSDN Subscriptions blog:

Effective June 30, 2007, MSDN Subscriptions will no longer be offering any activation versions of Office 2003 and Office XP from MSDN Subscriber Downloads or on media. We are working with the Office team to provide non-activation versions to replace these editions, and wanted you to be aware now so that you may download any needed Office 2003 and Office XP bits from MSDN Subscriber Downloads before they’re removed later this month.

Please note that the existing Volume License versions of these products will continue to be made available on MSDN Subscriber Downloads for MSDN subscribers who purchased their subscriptions through our various Volume Licensing programs.

Interesting. I’m not quite sure what the motivation is here.  Were they not seeing enough purchases of Office 2007 because everyone was downloading them from MSDN?