How do I install updates for worm elimination

Question

Operating system OSX 10.4.7, 1GB memory (41CB Free)
Office 2004 for Mac v. 11.2.5
Just received the following message from my ISP:
"Mail server report.
Our firewall determined the e-mails containing worm copies are being sent from your computer.
Nowadays it happens from many computers, because this is a new virus type (Network Worms).
Using the new bug in the Windows, these viruses infect the computer unnoticeably.
After the penetrating into the computer the virus harvests all the e-mail addresses and sends the copies of itself to these e-mail
addresses
Please install updates for worm elimination and your computer restoring.
Best regards,
Customers support service"
How do I eliminate worms and viruses?
iMac G5, Powerbook G4   Mac OS X (10.4.7)  

Answer 1

There are no known worms or viruses in the wild for OS X.
What is undoubtedly happening is that some windows user, who's machine is infected, has your email addy in their address book. Mass mailing worms will not only send to everyone in the infected accounts address book, but will use addresses from there to spoof the "from:" field in the sent emails.
There really is nothing you can do since it is not your machine that is the problem. It's some windows machine with your email in the address book, sending emails spoofed to appear as if they came from you.