GRC. Steve Gibson has put together a quick little app called DCOMbobulator that will test how effective the latest MS patches are protecting you from the lateset DCOM vulnerabilities, and it will also go ahead and disable DCOM on your machine.
As he says on the site though, if you run a NAT router or just about any type of personal firewall, the port DCOM uses, 135, will be blocked. (Assuming you haven't opened it for some other reason.) Disabling DCOM and patching still isn't a bad idea, it gives you an extra layer of protection and that's not really a bad thing. But I couldn't help from having this thought while I was reading the site this morning:
“There are at least 3 ways to prevent Blaster from hitting your machine, patching, disabling DCOM, or running a well-configured firewall. How the hell are so many people not doing any of these?”
Seriously, if you are connected to the internet in any way, (and if you're reading this, guess what? You're connected to the internet!) you should be running some sort of firewall! [Life of a one-man IT department]