As of today Microsoft allows to purchase Windows Vista Ultimate and Office 2007 Ultimate at a special discount price. The offer is restricted to students from german universities. Prices vary between 52€ (Office 2007) and 56€ (Vista Ultimate). Both products are available for immediate download only. A backup DVD is available for additional surcharge of 13€ per disk.
When registering with a valid eMail address of a german university (i.e. firstname.lastname@example.org) it seems it is not necessary to provide a certificate of enrollment.