Those $NtUninstall folders are created when you install a Microsoft Service Pack, a hot fix, or certain security updates. You may leave them there unless you need hard drive space. Visit, www.dougknox.com and check the utils section. MVP Doug Knox has an utility which can remove the Hotfix backup files without removing the hotfix.
They are the uninstall files for XP updates that you installed from windows
update.com
They can be deleted from explorer and then you can remove the unistall
entries from add/remove programs.