This is not directly relevant to your question but: you can get a big 22" BenQ monitor (to make home working much more pleasant) and a 1TB external HD (to help avoid total photo loss disaster) for a bit more than $330 from MSY. I would spend money there rather than buying the latest superduper high speed chip bc you're not that intensive a user (neither am I, I have more or less the same usage as you) and most new laptops can handle it easy.
Also, have you had a look at the whirlpool.net.au forums and seen what their advice is?
Also, don't forget to think about reclaiming GST if you're going on holiday any time soon.