A quick and easy way to list the installed Updates / Hotfixes via the command line:
wmic qfe get hotfixid

To output the list of installed Hotfixes to a file try:
wmic qfe get hotfixid > c:\installed-hotfixes.txt

If you want to quickly check to see if a specific Hotfix is installed try this:
wmic qfe get hotfixid |find “968930”

This tool is available in Windows 2000, Windows XP, Windows Vista, Windows 7 & Windows Server 2003/2008.