It must be tough to be on the Microsoft Office team. Year after year, you're given the same assignment: add new features to Word, Excel, PowerPoint and Outlook. New features that people will pay for, but that won't turn Microsoft's cash cow into a bloated, sloshing mess.

For the last few versions, Microsoft has mostly just shuffled around the existing features, reorganizing them into a Ribbon toolbar.

This year, the biggest news isn't the software, but how you pay for it.

Way 1: Buy the Office suite as you always have, for $140 (Word, Excel, PowerPoint, OneNote) to $400 (those programs plus Outlook, Access and Publisher).

Way 2: Buy an annual subscription to these programs for $100 a year. That plan is called Office 365.

Microsoft argues that this subscription offers all kinds of benefits. First, you can download and run the Office programs on up to five computers, including Macs and PCs. You can change which five they are at any time. (Windows PCs get Office 2013, with settings magically synced across computers. Macs get the older, less refined Office 2011 for Mac.)

If your home or office has a bunch of computers, you could save money; buying five copies outright would set you back $700. That's more economical only if you plan to use that increasingly ancient version for at least seven years.

With a subscription, you'll always get the latest version -- Office 2015, Office 2031, Office 2119 -- but, of course, you have to pay $100 a year forever.

You might be appalled at the notion of paying Microsoft an annual fee forever to get something you used to own outright. Or might like the idea of a fixed, knowable fee that keeps you up to date.

Either way, an Office 365 subscription gets you more than just five copies of the software. It also includes Office on Demand, which is the ability to download Office programs onto any Windows 7 or Windows 8 computer -- at a branch office or a friend's house, say. Touch up your slides, write up that proposal; when you log out, the downloaded Office software vanishes.

The SkyDrive is a free 7-gigabyte online storage disk for files that you want to access from anywhere, from any computer, tablet or smartphone with an Internet connection. In Office 13, it's more important; in fact, the factory setting is to save new documents onto your SkyDrive. And if you subscribe to Office 365, you get another 20 gigabytes. That's a lot of slides and spreadsheets.

Even that isn't the end of the pot-sweetening. The same $100 fee also buys you one hour a month of free Skype-to-phone calls.

So far, it must sound as if the only thing new in Office 2013 is how you pay for it. But there are also plenty of nips and tucks to the software itself.

The programs have a new design that matches the clean, rectangular lines of Windows 8's Start screen.