Hello Daniel
What is the software u have running now.. I can see the latest software for WLC 4400 as 4.0.206.0 on the download page...
With a normal cisco.com account, u will not have access to download softwares/TAC etc.. you need to have special permissions for that.. to download IOS, u can either contact your cisco partner, who supplied you the box or ask them to make a PICA ID for you.. PICA is a special partner Initiated access ID, which can enable features like IOS downloads for specific product which u have procured. You can talk to your Integrator to get this acccess..
Hope this helps.. all the best.. rate replies if found useful..
Raj