I currently have an iPhone 3G that I have paid for outright on Vodafone Australia. I am entitled to an upgrade now and want to go with the Nexus One. Problem is, Vodafone Australia is out of stock for some months.

I have noticed a few of them available on eBay. Is it possible to buy one from eBay and simply put my Vodafone sim card from the iPhone in it? Will this work?

Also, the same question would apply to my wifes phone. It's a Nokia N97 Mini. Can we use the sim card from this in a Nexus One?