nitro rig driver,
Port 135 is certainly not a port that needs to be, or should be, exposed to the Internet. Hacker tools such as "epdump" (Endpoint Dump) are able to immediately identify every DCOM-related server/service running on the user's hosting computer and match them up with known exploits against those services. Any machines placed behind a NAT router (any typical residential or small business broadband IP-sharing router) will be inherently safe. And any good personal software firewall should also be able to easily block port 135 from external exposure. That's what you want.
In addition, many security conscious ISPs are now blocking port 135 along with the notorious "NetBIOS Trio" of ports (137-139). So even without any of your own proactive security, you may find that port 135 has been blocked and stealthed on your behalf by your ISP.
From Microsoft:
COM Security Frequently Asked Questions
You will find additional ways to disable the port in the link above.
Take Care,
Richard