hey there. I live in australia and planning on getting a n900. because nokia isnt releasing the n900 to australia I have to get it from ebay, where they would be ordering it from the US most likely (don't know if its going to arrive anytime soon .. ) .

anyway because its not being released here and not providing any support I dont think updating over the air is an option, so was wondering if it can be updated through the computer??

hope its compatible with our network and new zealands also because i read that the n97 has alot of problems with the aussie networks, you know anything about that?

Hello, welcome.

There are two types of updates: firmware update (big thing, you normally use computer for this) and regular software updates, usually done OtA.
It is possible to update software using computer, just download the right package and put it on your n900. But this may be troublesome and is not recommended, as it may cause compatibility problems with different packages.

You can always use WiFi to connect to the Internet from your n900 and download necessary updates.

Simply put it, update over the air is possible as long as you have an Internet connection on the N900, this could be through your home or public wifi. It does not need to be over carrier's network.

Or another way is plug it into your PC and update using Nokia Update Software tool.