Have you seen the dpreview website? Loads of great information there to read and get confused over!

I use Nikon and of course I am going to say choose Nikon lol. My first DSLR was a D70s (which is the older version of the D90) and it is/was a great camera If you can go into a shop and feel both of them in your hands then give that a try. Sometimes it comes down to what feels more right in your hands too.

Be a bit wary of buying from Hong Kong. Make sure that the store has an Australian office because if there is any issues, such as warranty claims, then it makes it easier. Also you might get charged GST by customs if it's over $1000.

I've shopped locally at digitalcamerawarehouse or vanbar and they are quite competitive.

HTH