If you do not use Outlook Express for your email then this exploit has no ability to affect you. WHen they said in the bulletin "This could occur even if Outlook Express is not used as the default e-mail reader on the system." they are saying the exploit can happen even if your default mail client was netscape messenger, but you used outlook exprss occasionally.
If you dont use it, dont worry abou it.
If you dont use it, dont worry abou it.