Spent the last two days at work battling with a massive Nimda virus attack. It's scary what a big impact this thing had. It's incredibly infectious - it spreads itself by email, it scans for vulnerable web servers, it modifies your web pages with malicious Javascript, it scans for shared folders and copies itself into them, and it makes "guest" an administrator. Clever stuff - you have to admire (grudgingly) the guys who write these things!