Disable windows genuine advantage notifications installation wizard (Tested with Winxp)

1. Open IE and go to Windows Update site directly: http://www.windowsupdate.com
2. Click "Custom Install" to scan your system (Not Express Install).
3. After it finishes, please choose the update which you want to hide on the right pane and check the box "Don't show this update again".
(Note: If the checkbox "Don't show this update again" is grayed out, please first unselect the update.)
4. Restart the computer and this update should not be offered again.

Or,
If you want to get rid of the WGA wizard prompt that pops up during start up. just delete the annoying thing.
Goto   DriveLetter:\windows\system32  and delete the folder named KB905474.. no more annoyances.. Might be a good idea not to download anymore annoying things from Microsoft.