sophocleese....get yourself a virus scanning program if you do not already have one. (try inocculatit - workstation version if you are a win95/98 machine - it's free.....*grin*)
NEVER EVER EVER EVER "open" or "run" an e-mail attachment, or a download from the web, that ends in .bat,.com , or .exe without scanning it with a virus scanner (unless you KNOW it has been scanned and certified free by the person sending it to you.)
Ditto for ALL Microsoft Office documents received or downloaded.
Ditto for any floppies EVEN IF ALL YOU INTEND TO DO IS LOOK AT THE DIRECTORY!!!!
This is a bit simplistic, but will protect you a lot. Remember, new virii and trojan horses and macro-virii come out frequently and the best virus protection is next to useless if you don't update *it* frequently