People are already calling Conficker the worst worm in years, even though bloggers in Europe (where it’s already April 1) are saying it’s not doing anything.
It looks like ESet, makers of the fine NOD32 anti-virus software, have a page on how to remove Conficker, including what seems to be a free tool for its removal. Based on my limited reading, it seems that installing the latest security patches for Windows pretty much render your immune. But we all know people who don’t do that.
It looks like Conficker alters some Windows network internals, causing it to exhibit some different fingerprint characteristics when probed, so tools like Nessus and nmap are apparently able to detect it. Though Nessus is a gigantic problem, and I don’t have any machines with Conficker on my home LAN, so I can’t confirm this.