Well the cut-off for 2009 Parramatta was 90, but there's no guarantee that won't rise or fall in 2010.. (Campbelltown UAI cutoffs for Law rose by up to 4 this year - Arts/Law was ~94, Bus/Law was 91.45).
But based on the assumption that the cut-off stays the same...
There is a maximum of ten bonus points you can accrue. This includes BOTH Greater Western Scheme bonus points and HSC Subject bonus points.
So say you get a band 6 in Legal Studies, you will get 10 bonus points. If you don't get a band 6, you will get 5 bonus points anyway.
I was in the same boat, I would have gotten 10 bonus points for my mark in English, and 5 under the GW scheme, but only 10 'counted'.
But it's really important that you know, the uni definitely inflates cut-offs... I know of people who were offered a place in my course, 2009 cut off of 91.45 who only got around 78 for their UAI. I haven't heard of any lower than that, though.
Either way, if you don't get an offer, it's not hard to transfer in as long as your GPA for first year in another course isn't too bad.