Here is another way to prevent infecting your computer or sending out a virus undetected. This is a FREE program!
http://www.grisoft.com/html/us_index.html

This virus software is AVG. I have used it now for several months and it has detected email virus's coming into my system. It will perform an automatic scan and has a email protector in it. It updates its virus files on auto also. This program will catch all the virus's not just an email worm. Personal use of this program is free.

-Linda