Shajan, one of our development leads, wrote this wonderful article about integrating custom IFilters and IWordBreakers to extend SQL Server Full-Text search. The article describes authoring and installing Filters and Wordbreakers for SQL Server 2005. If you're having trouble deploying your IFilters or IWordBreakers on SQL Server 2005, this article is a must read !

http://blogs.msdn.com/shajan/archive/2005/12/09/Extending-SQL-2005-Fulltext-Search.aspx