I would install all Microsoft updates listed as 'critical' for your computer. Even if you don't use Outlook Express a hacker still may be able to expliot a security hole and attack or compromise your system.

If you have a hard drive space issue - upgrade.

Even better, just uninstall Outlook Express


start > settings > control panel > add/remove programs > Add/Remove Windows Components

go down the list and uncheck outlook express and anything else you dont use.