If you want to make sure you'll still be able to use the Internet when you wake up Monday, go to www.dcwg.org, click "Detect," and follow the instructions from there. That's the website of the DNS Changer Working Group, set up by court order to fix a bunch of servers that had been taken over by an Estonian crime ring to redirect millions of users to rogue websites. The FBI took over the servers and cleaned them up, but it doesn't want to be in the business of running DNS servers permanently -- so it's shutting them down Monday.
The date has been dubbed "Internet Doomsday" because everyone still using those servers will lose access to the Web once the FBI takes them down. The name is a little hyperbolic, given that only a few hundred thousand people are still on the servers. Still, it's probably best to make sure you aren't one of them. The DCWG website should be able to tell you for sure.
Or you can go straight to the source and type your DNS information into a website set up by the FBI at www.startribune.com/a1487. If your machine is one of those infected, the DWCG site will help you fix it before Monday.
Security firms like Norton also offer products to help wipe this type of malware from your machine -- though you'll still need to fix your DNS settings if you've been infected.