Tutorial in datamining
this book is useful

http://www.amazon.com/Data-Mining-Microsoft-Server-2008/dp/0470277742/ref=pd_sim_b_3

and here is some reviews and nice articles about it

http://blogs.msdn.com/b/jamiemac/archive/2008/10/02/data-mining-with-sql-server-2008.aspx

http://richardlees.blogspot.com/2008/12/book-review-data-mining-with-sql-server.html

slideshow
http://www.slideshare.net/PeterGfader/10-data-mining

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i also suggest watching these video tutorials by Learn it first 
as a start they can give you a basic but useful introduction

Data Mining with Analysis Services
http://www.learnitfirst.com/Course/165/Chapter/292/Data-Mining-SSAS.aspx

http://www.learnitfirst.com/Course/165/SSAS-2008.aspx

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chapter 11 of BI Architecture and Design Guide (best practices)
is focused on Data mining

http://biarchanddesignguide.codeplex.com/releases/view/6572