I had to install Windows Update Agent 3.0 to see SP2 in Windowsupdate but the actual installation fails as I removed Sidebar with Vlite. Check C:\Windows\Logs\CBS\CBS.log for any errors. This is the error I got: 2008-10-27 23:49:36, Error Failed to find the CixTarget for Container x86_microsoft-windows-sidebar_31bf3856ad364e35_6.0.6002.16489_none_d075dbb92406ec60\sbunattend.exe 2008-10-27 23:49:36, Error DpxException hr=0x80070002 code=0x020109 2008-10-27 23:49:36, Info CSI 0000000b@2008/10/27:21:49:36.075 CSI Transaction @0x3fa0360 destroyed 2008-10-27 23:49:36, Error CBS Failed to pre- stage package, package: Package_for_KB948465~31bf3856ad364e35~x86~~6.0.1.16489 2008-10-27 23:49:36, Info CBS WER: Generating failure report for package: VistaSP2-KB948465~31bf3856ad364e35~x86~~6.0.0.16489, status: 0x80070002, failure source: Stage, start state: 2, target state: 4 2008-10-27 23:49:39, Info CBS Exec: Processing complete. Session: 29964413:3383405396, Package: VistaSP2-KB948465~31bf3856ad364e35~x86~~6.0.0.16489, hr: 0x80070002 Here's the Update Agent update: Windows Update Agent