Majestic is correct. I live in Australia and am currently doing Maths Methods 4 (one step down from pre-tertiary level) - I'm in Grade 10. I will be studying Maths Methods 5 next year (pre-tertiary level) and this focuses on both integral and differential calculus (unlike level 4: just differentiation in regards to calculus). Please note that Methods is the pure mathematics course, and is generally what is required for entry into mathematics courses at universities/colleges
Next step up is Maths Specialised 5 (pre-tertiary; hardest difficulty prior to university/college) and this covers complex numbers, further principles in integration and differention, sets, sequences, divergence and convergence of functions, and an introduction to linear algebra. This would certainly give you a big leg-up if you do this (have to do Methods 5 in Year 11) if you intend to study further mathematics (and particularly analysis-based mathematics) at university/college.
I intend to do Maths Specialised in Year 12 myself (looking to dbl. major in maths and physics, in a combined degree with comp. sci.). My biggest interest is physics (and then comp. sci).
At the moment, I am working through Apostol's "One-variable Calculus" book which I found a copy of, and I would recommend this. It isn't too difficult (although I'm only ~80 pages through) but it certainly loads new information on to you quickly but in a concise and understandable manner. It will also teach you how to write proofs which certainly can't hurt regardless of where you want to go, post Methods 5. If you want to find out more about Apostol's books, I would suggest talking to Mathwonk (a resident maths professor on this forum)!
Hope this helps (and clears confusion about this subject).
Cheers,
Ulagatin
