As reported in various publications, including Daily Times, Pakistan has announced the start of DST for 2009 on April 15th at midnight. This information is subject to change as it has not been officially confirmed by a Pakistani government source.
Microsoft has produced a hotfix to implement this change for Windows Vista and Windows Server 2008. If interested in downloading this hotfix, please refer to KB 970084 titled: “A hotfix is available to update the Daylight Saving Time for the "(GMT +5:00) Islamabad, Karachi" time zone for the year 2009 for Windows Vista-based and Windows Server 2008-based computers”.
For other Windows versions, please refer to KB 914387 “How to configure daylight saving time for Microsoft Windows operating systems” on how to update the time zone registry key.