I was able to get “sphider” to work nicely for one of my sites.
Poke around the forums on there.
I even added support for searching inside pdf files. You can add support for other formats like .doc (I can’t think of any more but I think there are more).
I wish it had been a “one-click-install”… to that end, I recommend you go into your dh control panel, click suggestions (under ‘home’), search for the word ‘search’ and vote for the one about adding sphider or other search engine as a one-click-install. (I voted for it)