I think the two big issues are warranty and price.
Is the warranty world-wide? You'll need to check that. In addition, on laptops, I usually buy the extended screen protection plan since the failure rate on laptop screens can be considerably higher. You may want to consider that extended service and where it could work.
The second issue is price vs. Australia. I'm sorry I'm not up to speed on the current pricing system in Oz, but vs. the US, I did not find any deals on laptops in HK. Generally the systems were cheaper, and the selection greater, in the US given the simple economy of scale of the number of laptop purchasers in the States.
Another, odd thing, is the keyboard. I know the US and UK keyboards are slightly different (can be altered via software) but am not sure about Australia. Minor things, like the @ and the $£ thing being moved around might annoy you a bit.
And finally, I generally hate laptops. I buy a couple a year for my staff and I just hate them. Underpowered and overpriced status symbol toys. that break probably twice as often as desktops. I generally feel about 80% of the people with laptops don't need them. I actually use multiple desktops in my different offices / apartments carrying an external hard disk with me that I plug in when I arrive in a different place. My laptop comes into play on those nights in a hotel or on a plane to watch a movie. Of course your work may necessitate it, but just my two cents.