Well.....I've seen the .NET course materials provided by NIIT. They are good. But if you wanna learn and grip them NIIT course materials are not enough. You need to buy books for each topic. You won't be getting
VB, C# and ASP.NET in one book.
Well......if you're a beginner and want to learn the subject I'll suggest the Black Book.
Black boon on
VB.NET, C# and ASP.NET(with both
VB and C#)
In case of ASP.NET you may decide which language u'll be using for ASP.NET i.e.
VB or C# and buy the ASP.NET on that specific language. Or if you love both(as like me

) then you better buy ASP.NET(with both
VB and C#)
Black books helps you to learn step by ste[.
After you've learnt everything refer Wrox's books to get advanced. Actually Wrox are for professional field.
And for XML go for Beginning XML by Wrox. It's best.