Sharepoint WSS 3.0 discussion board alert tweaking of content types and workflows

This is a wss 3.0 sharepoint question relating to discussion boards.  I've been messing around with the content types, and think the discussions are a really powerful list type, but I want do to the following:

1. I have a custom field of type "People or Groups" called "people involved" on the Discussion Topic content type
2. I want to make a workflow in sharepoint designer 2007 such that every time a topic is replied to, to email the updated content/body of that discussion to the people in the 'people involved' group.
3. The workflow runs each time anything in the list changes and sends the email, i'm not using the sharepoint alerts, I want it to be able to be dynamically done from the people involved field

I am almost there, and if I change any field on the Topic content type itself, it will send out an, but it will not send out the email notification from the WF if a reply is posted.

I noticed that sharepoint seems to treat these topics as actual little lists, they show up as a list icon in SPD2007...

I'm still poking around and trying different things, but if someone knows a way to do this, let me know thanks!