You're right BOAC, while technically a .txt file in itself cannot contain a virus, it can contain information that is required by a virus/worm/trojan executable to deliver its payload. A quick gander on the Symantec site confirms this for the
w32.perrun virus for example:
If a .jpg or .txt file that has been altered by W32.Perrun is opened on another, uninfected computer, it will not execute malicious actions on that computer because the virus requires the presence of the Extrk.exe or Textrk.exe file for it to execute and append its malicious content to other files.
You learn something new every day
