What is the best way to ensure that presentations written on my mac display correctly on a Windows PC using MS Powerpoint? Currently I write my presentations in Keynote and export to .ppt (I find .pptx gives more errors like elements shifted around and in undesired fonts). I'd like to find the cheapest solution possible. I thought about NeoOffice, using Windows in a virtual machine, or MS Office for mac. I'd love to be able just to write them in Keynote and have some foolproof way of checking that the export will display correctly, but maybe I should just switch to writing in Powerpoint.