This is not a virus or any other kind of malware.
Some people have been wondering about mysterious entries appearing to their datebook to date 25 December 2030. The entries having title Santa and attached note containing a number (usually 0).
The Santa entries are an Easter egg (a hidden functionality) in wordsmith program versions 1.0c or older. For some reason the programmer thought it would be fun to put mysterious entries into the datebook.
This behaviour is harmless and shouldn't cause any problems. Blue Nomad has removed the Easter egg in the word smith version 1.0d.
Allow F-Secure Anti-Virus to disinfect the relevant files.
For more general information on disinfection, please see Removal Instructions.
Technical Details: Jarno Niemela F-Secure, January 2001