Ok. I did a search on the internet to make sure this wasn't already painfully obvious to everyone already. So, with the risk of stating the obvious, here is how you can integrate your SharePoint Portal Server 2003 search engine directly into your Office 2003 research task pane.
Load an office application and open the task pane (ctrl-F1). Open the research task pane, and click on Research Options
In the address type http://<SERVERNAME>/_vti_bin/search.asmx where <SERVERNAME> is the name of your SharePoint Portal Server 2003.
Now when you right-click on a word in an Office 2003 application and click Look Up, one of the search result groups will be pulling directly from your portal.