I've got a USB HDD and a NAS.

It costs a bit more but I would recommend a NAS anyday. I use one my company manufactures as it can either connect to a LAN or directly connect to your laptop's ethernet port. You pay a little premium over the USB one but at least all your systems can see the drive.

http://www.fujitsu-siemens.com/home/...ebird_lan.html

There are loads of others similar to this device and seeing as cheap personal NAS drives have dropped massively in price over the past couple of years it is worth the time to check a few out!

EDIT ADDITION:
Just had a quick look in the Aussie Google and came up with this list as they are all USB and NAS...
http://www.mittoni.com.au/nas-networ...37a85404f42641
I'm sure you can get slightly cheaper though!