Study materials for exam 70-310
To clear the 70-310 I've used the official MSPress book, and I can rate it 3 stars and a half over five.
I've also used the SAMS book "Building Distributed Applications with VB.NET", it's not intended for the exam but it covers a lot of topics. I already had it at home and I found it very useful.
I think that the most difficult part of the exam was the declarative security. Perhaps I found it difficult because I've not studied (nor used...) that topic very much...