Upgrade of EP 6.0 to NW '04s

Hi

I have a task to upgrade our EP 6.0 to its new release in NW '04s..

Kindly let me know where can I get useful documents like functional enhancements, pre-requisites, etc besides how-to guides.

I referred to the following sites but not of great help.

http://service.sap.com/netweaver

http://service.sap.com/upgradenw2004s

Regards

Madhu