If you're a parent or a business owner, then this weekend is a pretty sensible time to buy a new PC if you're looking for tax savings.
For parents of school-age children, there's the lure of the Education Tax Refund scheme, which offers a 50% refund off education-related expenses, which includes PCs. You can claim a potential deduction of up to $375 for a primary-aged child or $750 for a school-aged child (though the option isn't available if your income is so high you don't qualify for Family Tax Benefit Part A). Microsoft's announcement of an upgrade guarantee for new machines also means you might score a copy of Windows 7 further down the line, though this probably shouldn't be relied on heavily given the lack of detail from manufacturers in Australia so far.
For businesses, there's the one-off lure of the Small Business and General Business Tax Break, which allows a deduction of 50% (up from 30%) on assets costing more than $1,000 which have been acquired before June 30 2009. Businesses have until the end of the year to actually start using the asset, but need to have paid for it before the end of this financial year -- a handy reason to order a shiny new notebook or server at lower cost.