Getting rid of worms and viruses

[Ross Boylan <RossBoylan@stanfordalumni.org>]

I have been getting over 100 of these stupid MS virus emails a day.
Some are the "install this patch from MS" variety, while some are
embedded in returns of mail I didn't send.

This is driving me nuts, and certainly proves that Windows viruses can
be very harmful to Linux users, even if they can't replicate on Linux.
What do I need to take care of this (i.e., automatically delete the
junk)?  In particular, will anti-spam software (e.g., spamassassin)
take it out, or do I need anti-virus software (e.g., amavis)?

Is there a clear dividing line between anti-spam and anti-virus
anymore?  And do people have recommendations other than spamassassin
and amavis?

I run Debian systems at home and work, with somewhat different
configurations.  I plan to migrate home to exim4 at some point, so
really stuff that works with that would be best.  Here are some high
points of the systems:
Home: ISP (earthlink) -> dialup -> fetchmail -> exim3 -> mbox
Work: the internet -> exim4 -> courier IMAP server

I'm getting hit on both accounts, and work forwards to home for even
more fun.  Earthlink claims this is not their problem, which is an
absurd position, but I'm stuck with it for now.