As Rick kind of pointed out, a common feature of current viruses is to spoof the source email address. This means that the source address on the email you received most certainly is wrong. As Rick pointed out, the virus will look in the email software of the infected computer, grab addresses and use them to spoof the originating sender when it mails copies of itself to other addresses in the book.
Outlook Express is particularly susceptible to this kind of attack (especially if none of the security updates from MS have been installed) - but that only tells you that the likely true source is using that software, nothing more.
Hopefully, you know the email had a virus because your protection software caught it for you. It should have also told what kind of virus it thought it was. Take that name and go to
http://www.sarc.com, and look it up, including the details on how it works - you'll probably get a better explanation.
What all this means is that Rick almost certainly didn't email it to you (as he sounds like he is well protected), but somebody who at some time had email correspondance with Rick did - that could be a lot of folks!
Added in edit: I just noticed that your original post mentioned Klez32.worm - that one definitely spoofs the source address as Rick said. There's also no guarantee that others who get the mail from the same computer will see Rick as the source, it may be some other address found on the infected computer.
