You would want to know what they are doing with their sites and why they are linking to you. You might also want to link to them. Then you can contact the webmasters of those pages and request that they change to the new addresses, so you don't lose the link. Links have become even more important recently as major search engines, including AltaVista, have begun to use the links to a page or a site as one of the factors used in determining which pages will appear higher in a list of matches. Pages and sites with lots of links from other sites with related content are considered important when calculating the ranking for a particular query.
Every match is equal.
And this is one important instance where the person submitting the query may well want to see all the results, rather than being limited to just the first 200.