bigjim...
Veteran "spammers" have ways of getting around spam filters...
The trick is to try and outsmart them. You've taken the first step in only adding senders in your address book. While these spammers have found a way around that...you may want to tweak your spam filter settings in Outlook 2000.
Here's a good read.You may also want to look for a better "free" spam filter you can configure with your version of Outlook.
Just do a Google search for Outlook Spam Filter...and you'll be presented with a lot of recommendations.
Personally...I use Thunderbird...
It has a great Spam Filter...does exactly what I want it to do.
Hopefully the information I've provided will help in some way...please keep us posted...