You need to stop the Windows Update service, rename the software distribution folder then restart the service, as follows :1. Make sure you are logged on as an Administrator and go to the Windows Orb (Start) > All Programs > Admin Tools > Services then right-click the Windows Update service then click Stop.2. Go to the Windows Orb (Start), type %windir% in the Start Search box and then press Enter. Locate and rename the SoftwareDistribution folder to, say, SoftwareDistributionOLD. 3. Go to the Windows Orb (Start) > All Programs > Admin Tools > Services (Provide the Administrator password or confirmation if prompted to do so) then right-click the Windows Update service then click Start. 4. Try to download the missing updates again.
Could run registry mechanic or the temp and registry cleaner in ccleaner to clean out the temp items. I'm not familiar with vista, but with xp update problems that works like a charm.