Halon- you may want to check out this link at snopes.com-
http://www.snopes.com/crime/statistics/ausguns.asp
The site makes a lot of the cases I was going to make about statistics, particularly around correlation vs. causation, the danger of using 1 year of stats, and the lack of viewing broader trends and other contributing factors. MOST importantly, in the first few years since the ban was incurred, the rates of armed robberies dropped drastically.
Along the lines of crime rates, it's important to note that the stats that you quoted (as snopes point out) are measuring crime in absolute terms, not in rates. The homicide rate for Australia actually dropped in the years immediately following the gun ban. Since the population of Australia was expanding, measuring the absolute # of crimes is not accurate- you have to measure the number of crimes vs. the total population (which was growing pretty quickly).
Also important- Australians never had a constitutional right to own firearms. The buyback affected a very small group of people and didn't even take away all of their guns.
More stats, taken from the Australian Bureau of Statistics, show the latest crime data from 2005. A few excerpts:
In 2005 the victimisation prevalence rate for household crime was 6.2%, compared to 8.9% in 2002. Comparisons with 2002 for all selected types of household crime showed statistically significant decreases in the prevalence rates for:
* break-in, where the victimisation rate in 2005 was 3.3% compared with 4.7% in 2002
* attempted break-in, where the victimisation rate in 2005 was 2.6% compared with 3.4% in 2002
* motor vehicle theft, where the victimisation rate in 2005 was 1.0% compared with 1.8% in 2002.
The attempted break-in victimisation prevalence rate for Australia decreased to 2.6% in 2005 from 3.4% in 2002. Across the states and territories, decreases occurred in:
* New South Wales (2.7% in 2005 compared with 3.7% in 2002)
* Queensland (2.9% in 2005 compared with 3.8% in 2002)
* Western Australia (3.0% in 2005 compared with 4.4% in 2002)
* Tasmania (2.1% in 2005 compared with 3.3% in 2002).
Here's the link to the data-
http://www.abs.gov.au/AUSSTATS/abs@.nsf/productsbyCatalogue/669C5A997EAED891CA2568A900139405/