I am planning for [...] exam in few months.
It's better to aim for version 4.0. The exams for version 3.5 will be retired next July, so you don't have that much time to complete them.
If you wish to get a certification on asp.net 4.0, I suggest that you take exam 70-515, which will give you the certification "MCTS: .NET Framework 4, Web Applications." This is the link to the exam description page:
http://www.microsoft.com/learning/en/us/exam.aspx?ID=70-515
Note that the page contains a section on preparation materials. The Microsoft Press book listed there will help you prepare for the exam.
Alternatively, you may consider pursuing a newer certification (4.5):
http://www.microsoft.com/learning/en/us/mcsd-web-apps-certification.aspx