Wll first, dont worry or be depressed too much, btu you need to choose courses that may have less demand so that either the uai will remain or drop. Computing has been having lower demand due to the issue of outsourcing and such, which is also something that is being experienced in high schools; well fo example my old high school no longer offers IT VET due to not muc demand, however i do not know the overall statistics. So pick many back ups but also put your ideal unis too, you might get lucky.
I got into uni through my last preference, and in actual fact i was the last person allowed in; i was pretty stoked. My uai was only 66.50 and so was my courses entry mark, and i know how you would feel, but i just recently met up with my old high school buddy who didnt get into uni, even though he had a higher uai than me, due to the fact he chose high uai/demand courses.
Also, consider the alternative pathways like TAFE and such. I just went to sydney and at Market City they have an info stall on level 4 i think on special options for those who may want to enter uni but may seem unable to such as UWS's SWIC, UTS's Insearch and SIBT among other options. Think about them, as those speical schools offer diplomas that can also account for entry and credit to your future degree.
To assure you, no there is no other criteria to be assessed upon unless the course specifically asks of it, e.g. UTS's degree in accounting and many Music and Design/Arts courses. So if your uai is higher than the course entry you are in, but remember last years uai mark is not this years, you will only know when you receive your offer on the day...
hope it helps, and try to be optimistic, there are many options available.
edit:
actually, ive just found some info about IT
http://www.smh.com.au/news/national...e-in-it-courses/2006/12/02/1164777848896.html saying that there is going to be a greather demand in IT , so keep in mind finding a back up course you will be willing to enter.