MS exams are not helpful

Those questions are way too detailed for most interviews. Software technologies change too fast for the technique of memorizing Q/As to work. Besides they are useless to the daily work.

I would recommend to focus on one area first, say, web dev in .NET, be it AJAX, WPF, Silverlight, read MSDN articles often, pick some reference projects and go through their source code in detail, to the point you can write a similar app yourself. You'd pick up a lot more by doing that. Of course this requires far more resolve and brain cells than memorizing some drop-dead Q/As.

my $0.02