My company is slowly making the switch to C# and I would like to be a developer for them someday (currently a QA). I figure that I should learn C# for this, but am not sure what tool I should use. They currently use VisualStudio.NET 2003 for C++ and C#, I believe. I have access to VisualStudio 2005 Professional and VisualStudio.NET 2003 Pro through my college. Which one should I use?