Microsoft ends support for Office XP and Vista SP1 on 07/12/11
http://www.computerworld.com/s/article/9218164/Microsoft_to_retire_Office_XP_Vista_SP1_next_week

QUOTE: Microsoft will retire 2001’s Office XP and the first service pack for Windows Vista next week, according to the company’s published schedule.  Both Office XP and Vista Service Pack 1 (SP1) will exit all support July 12, this month’s Patch Tuesday. That date will be the last time Microsoft issues security updates for the aging suite and Vista SP1.  Vista users must upgrade to SP2.

Microsoft supports its business products for 10 years, the first five in what it calls “mainstream support,” and the second five in “extended support.” The biggest difference between the two phases is that in the latter, non-security fixes are provided only to companies that have paid for special support contracts.