While the figures gained should be almost identical in most cases using a site like
Speed Test - Home - Oz Broadband Speed Test to measure speed should be more accurate for aussie users given the server location.
The basic test does the same thing however it's starts with a local based connection not an OS connection. ozspeedtest has also been the main speed testing site of aussie ISP's and network admins for more than 5 years.
Also ozspeedtest gives the option to test several different file sizes rather than a "one size fits all" connection test. Using one large file download of 9 or 15MB (no matter what your connection speed ) as the test will always result in more accurate results because of the way data is transferred on the net.
Using one 2 minute test from a site will give a figure that may or may not be close to the total of figures you can get from a site like ozspeedtest but over all testing on a wider range of files (not at once) will always gain you better results which can be handy if you looking for bottlenecks rather than just figures that show your connection is faster than someone elses.
Having said all that its still a preference thing, none of us are ever going to get our full rated speed from our connections because there is too many overheads but it's not hard to make a site that says you are getting it.