I have found the easiest way to keep up to date with new KB alerts for MOM and other products is to sign up for e-mail notifications from KBAlertz.
Add your e-mail and a password and chose as many categories as you like to get regular e-mails informing you when Microsoft has released a KB on that subject (the content is aslo included in the e-mail). And it is free. The only downside is that if you sign up for multiple technologies then they all come in a single e-mail.
They also have an RSS feed for MOM 2005 KB articles
The MOM 2005 page at Microsoft is
which has the KB search box already pre filtered for MOM 2005.
I find KBAlertz easier to use.