Step back a second and think about why you're taking music psychology.
90% chance because you wanted a 'fun' and 'easy' breadth.
So miss that one and go to the one you actually care about.
hmmmmm good point (although i also chose it cos i need to do it for the diploma of music which i'm hoping to get into)
Hmmmm thanks for all the input so far guys, i've got a lot to concider and people have all made good points:)
also rustic, would you mind sending me those full notes anyway? i'd like to have a look at the course 
Haha oh, sorry for making that assumption then, I just know a lot of people who have taken it/are taking it because they think it's the best of a variety of poor options and the assessment is easy.
But yeah, when I had a clash last year it was basically based on resources. Only one of them was recorded, so even though I cared about the other subject more I was forced to go to the one that wasn't recorded (it also didn't have slides on the LMS, a nightmare).
But my other subject, luckily, even had video capture rather than just audio so I could watch the slides play along with the lecturer speaking.
It was quite handy.
So maybe base it off resources. If they're both recorded I would go to Vector Calc first week (its lecture is likely to be more intensive than what the first week of Music Psych would be) and then Music Psych the second week and base your decision on which was hardest to catch up for

Or you could always alternate.