Microsoft Security Essentials - How to manually update
This link is handy for manually updating PCs with MSE installed, esp. if there is no Internet connectivity. After updating MSE signatures, it's beneficial to perform a QUICK or FULL SCAN with these latest definitions to ensure your system is malware free. It's a very easy process in downloading the applicable file, clicking on it, and it installs in about one minute.
http://support.microsoft.com/default.aspx/kb/971606