Looking for a good search engine for my website (for internal searching, not web)

Can anyone recommend a good search engine? The one that my front page offers is pretty lame. I want to be able to have a search box on my site (like www.hp.com or www.cnet.com etc) I don't want to use one of the free ones, because I don't like the links to other web sites.
I want one which will let me have a custom search page, will index itself (I don't want to have to set up key words)
Any recommendations?
Thanks!