This is not an ADSL modem, but will plug into one to give wireless net through your home/office, and a four port switch/hub built in. Only 802.11g (has WPA2), but still cheap. Bought one for my in-laws today and seems to be working well.
Comes with a CD that will install things really easily with a wizard, or you can login through your browser to http://www.routerlogin.net/ (IP seems to be 192.168.1.1 or 10.0.0.1 if your ADSL modem is using the former) and configure it manually.
There's also a Belkin wireless router that seems very similar and is also $29 here;
http://www.wireless1.com.au/ProductListing.aspx?Code=BELF5D7…
I've got the non wireless version of this router. Works fine :)
EDIT: from memory is 10/100, not gigabit. no wireless n etc