>You may want to look at Lucene.NET - it's free and the search is excellent (and easy to incorporate into a .NET app).
>
>http://incubator.apache.org/lucene.net/

Changing a search engine like that is not something that is easy to do. It requires a lot of preparation and it usually done once every 7 years, in my experience so far in this product. The policy is also to use, since the 2000, no third party at all. This allows the framework to be transported and scaled at any time. But, thanks for the reference