Windows 8, OS X upgrades by the numbers

Computerworld - Like 2009, this year is one of dueling operating system upgrades, when the two biggest OS rivals face off with new editions.

We've covered both the Windows 8 and OS X Mountain Lion upgrades, and spelled out what's known so far about their prices, release dates, delivery methods, upgrade paths and more.

Now it's the turn of the numbers to tell their story.

0 The price of an upgrade to OS X Mountain Lion for buyers of new Macs who purchased their Lion-powered systems starting June 11. The program, called "Up-To-Date" by Apple, continues as long as either Apple or its authorized resellers sell Lion-equipped Macs. The free upgrade will be available from the Mac App Store after buyers fill out a form to be posted on this page of the Apple website.

It's also what a Windows user will pay for the Windows Media Center add-on after upgrading to Windows 8 Pro. The add-on, which will come with a price of some sort after Jan. 31, 2013, lets Windows 8 PCs play DVDs.

1/10th The amount a Mac owner spends to upgrade five machines compared to what a Windows user pays to do the same. Unlike Microsoft, Apple lets customers install Mountain Lion on all personally-owned machines.

1 The number of choices Windows and Mac users have for their upgrade editions.

Although Apple has long practiced one-size-fits-all, Microsoft followed suit for the first time this year when it offered only Windows 8 Pro in both the $14.99 and $40 deals. Previously, Microsoft has provided multiple upgrade versions so that, for instance, someone running Vista Home Premium upgraded to Windows 7 Home Premium, not to Windows 7 Professional.

2X How much more Windows users will pay for their upgrade to Windows 8 Pro than Mac owners will pay for theirs to OS X Mountain Lion.

3 Number of previous versions of Windows that can be upgraded to Windows 8 Pro: XP, Vista and Windows 7. That's one more than either Vista or Windows 7 covered. Vista's upgrade was available to Windows 2000 and XP machines, Windows 7 to XP and Vista PCs.

Also the amount of free space on a USB flash drive necessary to create bootable installation media for the Windows 8 Pro upgrade, useful as backup install media or to do a "clean" install by wiping the hard drive before upgrading.

5 The maximum number of Windows PCs that users can upgrade to Windows 8 Pro using the "Windows Upgrade Offer" for people who purchase new machines, or the $39.99 upgrade for owners of existing machines. The limit is meant to stymie businesses that might try to take advantage of the low prices rather than subscribe to expensive volume licensing contracts such as Software Assurance.