Hello Alice,
I was at home working with my wireless network and I don't know if it is related but I tried with other network, connecting my laptop with ethernet cable (without wifi), and when I select the "All Availabel Sites" option as you recommended, it worked fine, and shows the list as you. Even the option "Freescale KDS Site Update - http://freescale.com/lgfiles/updates/Eclipse/KDS" now works well and display the following list that I needed:

Although I think it isn't necessary, my OS is Windows 7 Home Premium, and installed KDS in the default path (C: \ Freescale \ KDS_3.0.0).
Thank you very much for your help, was very helpful.
César