I was searching for the WinSDK for .NET 3.5 and found it on the MSDN website. This is very essential especially when you are about to learn a new technology, it is worth hundreds of books out there!!
Check it out here: Windows SDK for Windows Server 2008 and .NET Framework 3.5 (http://www.microsoft.com/downloads/details.aspx?FamilyId=E6E1C3DF-A74F-4207-8586-711EBE331CDC&displaylang=en).
Hope it helps,
Regards
Tags: Windows SDK, Windows SDK .NET 3.5, Windows SDK Server 2008