From a self-proclaimed design expert:
1. The writing can become difficult to see on top of the images. Don't be afraid to put a black box in the top corner of the image that blends into it. This will not only make writing easier to see but can be aesthetically pleasing if done correctly.
2. Get a better resolution school logo/images all around.
3. Nice use of negative space.
4. The flash of image changes is a little quick for my liking - even if it were slowed down by a half second it would be less sudden.
5. As you have a rounded rectangle for the home page, that squared buttons can look odd if you look at them long enough. Even just extending the maroon down may look better?
6. The header should link to the home page.
This is a very good website and a MASSIVE improvement from the original. Consider what I said but I don't have much to back me up for website design - I'm more used to layout and stuff. You obviously have more expertise than me for this. Very good job on keeping it professional looking (it is a school after all) with a still pleasant feel.
Much better than the newly redone
http://resources.mhs.vic.edu.au/mhs/