There has been a lot of anxiety about what will happen on April 1st. Typically, you pull a prank on a co-worker. This year, a virus will do... something. Maybe.
A conficker variant, also know as downadup or kido, is scheduled to alter its activity tomorrow.
I recommend reading up on what Conficker is, what it does, and what is being guessed it will do. A good start is the SANS diary:
http://isc.sans.org/diary.html?storyid=6043
A really good timeline is posted here:
http://lastwatchdog.com/evolution-conficker-globe-spanning-worm/
And a rather amusing FAQ about the virus is here:
http://www.f-secure.com/weblog/archives/00001636.html
For last minute removal, you can find Conficker/Downadup tools here:
http://download.eset.com/special/EConfickerRemover.exe
http://www.symantec.com/security_response/writeup.jsp?docid=2009-011316-0247-99
http://data2.kaspersky-labs.com:8080/special/KidoKiller_v3.3.3.zip
http://www.mcafee.com/us/enterprise/confickertest.html
ftp://ftp.f-secure.com/anti-virus/tools/beta/f-downadup.zip
http://www.bdtools.net/how-to-remove-downadup.php