I came across a number of products from cognos  , like impromptu , Business Objects , cubes and a whole lot of others. I am an experienced IT professional and have some idea abt datawarehousing . But to start with the reporting tools , I am confused . Would learning abt one , say cognos impromptu help me work with the others , say BO or crystal reports ? or these are separate systems  completely different from each other and each needs a separate study ?
Also , the forum told me that cognos help is the best material available for self study . Can someone also tell me how I can obtain this ? Do I need to contact IBM to procure the material ?I tried looking over the internet but couldnt find the best place to get cognos help....
 

thanks , appreciate ur help 

guys...can someone plz tell me what are the best study books/ guides / online reference tutorials for datawarehousing concepts...I have to study ETL informatica and cognos...