#0 - Dec. 15, 2007, 12:58 a.m.
http://blogs.msdn.com/vsxteam/archive/2007/12/15/AddOn-Studio-for-World-of-Warcraft-released.aspx
Q u o t e:
The only thing it downloads, I believe, is .NET Framework 3.5 and any necessary windows updates required for it. If you install .NET 3.5 yourself, the installation for AddOn Studio goes quite smoothly.