Windows Update "Select updates to install" gives blank list on Vista/Windows 7
Windows 7 Forums - Windows 7 - windows update doesn't show details
Windows Vista forums - Windows Update "select updates to install" screen is blank
Windows Vista Forums - Vista - blank list in "Select updates to install" Windows Update
Windows 7 Forums - Cannot select updates/ updates don't show up in the select list.
Windows 7 Forums - Can't see updates list on Update window
The WinVistaClub - Windows Update Page Is Blank In Windows 7 or Vista.
Many suggestions to reset Windows Updates, either with Microsoft Fix it 50202, available here, or by stopping wuausrv and renaming the %SystemRoot%\SoftwareDistribution folder and restarting wuausrv.
Found two semi-related blogposts:
Aaron Stebner's WebLog - Steps that might help fix Windows Update errors and a blank Windows Features dialog in Windows Vista
Raymond.CC Blog - FIX Blank or Empty List in Vista Turn Windows Features On or Off (OptionalFeatures.exe)