Hi Syed,
The default viewer is the HTML Interface for Webi in BI Launchpad and it does not have as many data sources available in it. If you switch to the java based Applet Interface then you will see it shows more data provider options.
The Webi User guide covers the interfaces
http://help.sap.com/businessobject/product_guides/sbo41/en/sbo41sp7_webi_user_guide_en.pdf
Section 1.2
Thanks
Jonathan