There are some features of Windows Azure that you will need to get to from the original Azure Silverlight portal. In our case we needed to access Windows Azure Traffic Manager components. The link to the old portal is stated as follows on several MS articles.
This link however, forwards you to the new Azure portal. To get to the Silverlight portal you can click on your LiveID in the upper right hand corner of the new Azure portal and click on the “previous portal” tab in the drop down.