Once you log in, run shutdown - a from a DOS Prompt then follow the directrons on removing patches. Take this as a lesson to run Windows Update and install critical updates.
Most likely your comp might restart before you have a chance to do anything, so if you run Win XP, enable the Windows Firewall (or any firewall you might have). You can also disable RPC for the moment (I forgot how to go about doing this, I'll look into it if you need) so that the worm can't exploit it.
Afterwards, I suggest you grab the updates from Microsoft (dunno which one it is that prevents blaster from affecting you, I'll have to look into that too).