Microsoft Office Professional Plus 2013 is a 60-day trial build of Microsoft's flagship productivity suite.
The program includes the 2013 versions of Word, PowerPoint, Excel, Outlook, OneNote, Access, Publisher, and Lync. These won't run on Windows XP or Vista, unfortunately. and you can't install them alongside an earlier release of Office, either. It's one or the other.
The download link here takes you to the Microsoft site, where you'll need to register with a Microsoft account, and will be given a product key (make a note of this, or print it, as you'll need the key to activate the program later).
And once the process is complete you should be able to download the build. Either 32 or 64-bit versions are on offer, and both come in the form of an IMG CD image.
One potential small irritation here is that the 64-bit image is 769MB in size, so you may find your disc burning software says it's too large to save to a CD, and can't be burned to a DVD. If you have similar problems then the simplest solution is probably to use something like 7-Zip to extract the contents of the IMG file, then burn the contents to a DVD, just like any other data disc.
A simple way to get a free look at the next incarnation of Office