Hi Daniel!!!
I am a spanish guy and I have also been thinking of going to australia to make a journey around the country. In fact, it is one of my dreams. I am also 23 and I will be free since june 2008.
I have no experience traveling by bike, but I am fit and lately quite sportive, so I guess would not have any problem.
so, we will keep in touch,
byeeeeeeeee!!
Jon