OK, after screaming every time I got a copy of MyDoom in e-mail, I've finally done something about it and thought that others running linodes might like to share in the knowledge.
The solution I found uses
ClamAV which is a pretty sweet Open Source virus scanner. The current virus database detects 20687 viruses! It even includes a utility that updates the virus database automatically.
It was really easy to install (just follow the documentation found at the site) and it seems to be really fast.
If anyone has questions or need help installing, drop me a line. I'm no expert, but I did manage to get it working (after realizing that my sendmail is reading /etc/mail/sendmail.cf and not /etc/sendmail.cf)
--James