It is relatively easy to build a data warehouse based on SQL server using Analysis Services.
The simple part also depends on your requirements.
To display the cubes and deliver reports you can use Cognos Reportnet/Powerplay or BI.
Also with SQL 2005, Reporting Services is available.
Keep in mind though, PowerPlay is best cube viewer in the world.
If you buy a package like SAS, you will buy lots of limitations as well. AS gives you freedom.
Kalman Toth, Database, Data Warehouse and BI Architect
The Best SQL Server 2005 Training in the World