If you need PDF files in your search results, the steps listed by Stan Spotts in his post WSS 3.0BetaTR PDF search configuration and setup have been confirmed to work under WSS 3.0 RTM.

As an added bonus, WSS 3.0 RTM will actually show lines that contain your search term and highlight the term!

S.S. Ahmed has a detailed article that specifically for MOSS, but it is useful as well, especially for the instructions on getting the PDF icon to display: http://www.sharepointblogs.com/ssa/archive/2006/10/13/13812.aspx.

Nathan