If you haven't yet retired your old Windows XP or Vista operating system, Microsoft would like to encourage you to do so now. The Customer Preview of Microsoft Office 2013
is designed for Windows 7 and 8 operating systems and won't install on anything older, including Windows XP and Vista. Office 2013 isn't expected to be available until - you guessed it - 2013, but Microsoft is already beating the promotional drums and made a preview of the consumer version available today. You can sign up for it at Microsoft's site
If you are running WinXP or Vista and you're willing to upgrade, there's some good news: Microsoft announced earlier this month that it wil make the Windows 8 upgrade $39.99 when Windows 8 is officially released. The Windows 8
upgrade (not Office) supports operating systems as old as Windows XP. You'll just need to find a friend with a newer OS if you want to check out the preview of Office.
Microsoft's Office Customer Preview FAQ
has some worthwhile information for anyone planning to take Office for a spin. A couple things to keep in mind: you can install the preview alongside your current Office without affecting it, and you'll need to be at Release Preview or higher if you are testing Windows 8.