In all honesty, get yourself upgraded to VS 2010. If you are serious about becoming a professional in Silverlight development, version 4 has the most bang-for-your-buck.
Not all the newer technologies are supported for Silverlight 3 and all the latest cool tutorials and project examples tend to be in VS2010/SL4.
You also should not ignore patterns like MVVM and libraries like Prism & MEF as they are rapidly becoming commonplace for Silverlight projects. There is more danger of you getting into Win-forms-style bad habits if you use a Win-forms style approach to Silverlight at first.
Here is a simple explanation of MVVM for Silverlight:
http://openlightgroup.net/Blog/tabid/58/EntryId/89/Silverlight-View-Model-Style-An-Overly-Simplified-Explanation.aspx
These videos are a good introduction to creating/understanding Prism-based projects, specifically for Silverlight:
http://channel9.msdn.com/posts/mtaulty/Prism--Silverlight-Part-1-Taking-Sketched-Code-Towards-Unity/
It includes him building an Outlook-style application using prism (with full source provided).
The codeplex project, full source and documents etc, for Prism and soon MEF is here:
http://compositewpf.codeplex.com/wikipage?title=Getting%20Started&referringTitle=Home
Prism was created by Microsoft and will soon have a final release of version 4 (including MEF).