That is a bit of a general request, isn't it? This forum is primarily focused on technical issues, you might want to search for case-studies and other publications by datawarehouse gurus to get some insight into the matter. Even then I would narrow the scope down to get more grip on the matter, cause 'the impact of ' is a very broad approach.
Perhaps more interesting is to evaluate the usefulness of DWH for different type of companies... T. Blom
Information analyst
tbl@shimano-eu.com