:Vista SP1 Won't Install on Dual-boot Systems: Microsoft
Vista SP1 Won't Install on Dual-boot Systems: Microsoft Jul 31, 2008, 13 :00 UTC (7 Talkback[s]) (5828 reads) (Other stories by James Bannan)
"Microsoft has excused itself by saying Vista SP1 contains an update to the BitLocker feature, and replacing the bootloader is a necessary prerequisite just in case the system being serviced contains a drive encrypted with BitLocker or worse, an encrypted boot partition."