I've never had good luck with Norton. I use EZ Armor. I got 5 or 6 of those emails this morning and EZ Armor alerted me that they were a high level threat. I cleaned my cache, deleted my cookies and my temporary internet files. I don't know if that eliminated whatever it was that was causing me to get the emails, but I haven't gotten one since.
I've had my main email address for a long time, and I hate to change it. Most spam comes because you have posted in a forum online some time in the past, or have gotten on someone's email list that was sold and got into the public domain.
I'd say it's a good idea to delete the temp internet files fairly often. I don't delete my cookies because some of them have data I need to access sites where I am registered, but I do comb through them once in a while and weed them out.
CT Cookie Spy allows you to easily see what you have and delete what you don't want. And Norton and AdAware deal with most of the malign cookies.
None of those things affect whether you get sent the messages. That's caused by someone else being infected and sending you the email messages.
The infected computer will, therefore belong to somebody that has your email address in their address book. That's where the worm finds addresses to send to.