i think arts gets bagged out because of the lack of direction and employment opportunities. say one person does a b. psychology and another does a b. arts with majors in psychology, the b. psychology student would have more recognition because of the name of the degree..
well thats just what i think...
as for what subjects you should do, do what interests you. if you like economics, do economics, if you like software development, do software development. what i'd suggest is that turn up to some of the lectures on the other subjects you are intested in for the first week, and then if you like the subject, transfer into it!! but be sure to cancel your enrolment in any of the other subjects you don't want to do so that you don't incur any unnecessary hecs debt!