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Get your cheap Windows 8 upgrade now

Microsoft's $39.99 Windows 8 upgrade special ends Thursday, so you may want to buy it now even if you don't plan to install it yet.

Screenshot by Lance Whitney/CNET

Anyone even considering Windows 8 should grab the upgrade special now before it expires this week.

Users of Windows 7, Vista, and XP can purchase the upgrade to the new operating system for just $39.99 per PC. Those of you who bought Windows 7 after June 2 last year can score Windows 8 for just $14.99. And that's for the Pro version.

After January 31, the upgrade price skyrockets to $119.99 for the regular edition and $199.99 for the Pro version.

However, Windows 7 users who bought their computer between June 2 of last year and January 31 of this year still have until February 28 to register for the upgrade.

OK, that's fine, you say, but I don't want to upgrade to Windows 8, at least not right now. Well, you can buy the upgrade this week, but you don't have to use it. You can install it anytime in the future and on any computer you want.

Here's how:

Windows 7, XP, and Vista owners should head over to the Upgrade now and save page to grab the $39.99 offer. Windows 7 users who qualify for the $14.99 price can surf to the Welcome to the Windows Upgrade Offer page instead.

After asking for your region and country, the $14.99 offer page requires you to enter your name, e-mail address, and details on your Windows 7 PC purchase. Microsoft may also ask for your Windows 7 license key for confirmation. You'll then receive an e-mail with a promo code and a link to download the upgrade.

From that point, both the $39.99 and $14.99 offer work the same. Clicking on the Windows 8 upgrade link downloads the Windows 8 Upgrade Assistant in the form of a file named Windows8-UpgradeAssistant.exe. Running that file checks your current PC for Windows 8 compatibility issues and eventually takes you to an online purchase page where you can buy the upgrade.

The order confirmation page will ask for a promo code, which qualifying Windows 7 buyers can enter to receive the $25 discount. The rest of you will leave that field blank to keep the price $39.99. After you've sealed the deal, the Windows 8 installation downloads.

After a good 15 minutes or so, Windows 7 and Vista users will see a screen with three options: 1) Install now; 2) Install by creating media; 3) Install later from your desktop. Options 1 and 3 are geared for those of you who want to upgrade your current PC. But if you don't, simply choose option 2.

The option to install by creating media saves the Windows 8 installation onto a USB drive or as an ISO file. You can burn that ISO file onto a DVD. Once the Windows 8 upgrade is stored on your USB stick or DVD, you can install the OS anytime in the future. Only the cheap upgrade price expires this week, not the actual installation. So you can install Windows 8 a year or two years from now, if you wish.

Further, you can install the Windows 8 upgrade on any computer you choose. It doesn't have to be the one onto which you downloaded the upgrade file.

Prior to the installation, you can also tell Windows 8 to keep your existing settings, personal files, and apps, an option that varies depending on your current version of Windows.

Or you can tell it not to keep anything if you want to do a clean install and start fresh.

Windows XP users face a greater challenge in performing the same trick. Running the Upgrade Assistant on a Windows XP computer offers only two options: 1) Install now or 2) Install later from your desktop. There is no option to install by creating media. But here's one possible workaround.

Instead of running the upgrade on your Windows XP computer, find another computer running either Windows 7 or XP. You can run the Upgrade Assistant on that computer, choose the option to install by creating media, and save the file onto a USB stick or burn the ISO onto a DVD. You can then use that USB drive or DVD to upgrade your Windows XP computer at any point down the road.

But if you do plan to upgrade Windows XP, which is likely to be a 32-bit version of Windows, you must run the Upgrade Assistant on a 32-bit version of Windows 7 or XP. That process then creates a 32-bit installation of Windows 8. This has to be done because you can't upgrade from a 32-bit version of Windows 7, Vista, or XP to a 64-bit version of Windows 8.

If you plan to install Windows 8 cleanly and wipe out XP, then you can run the Upgrade Assistant on any Windows 7 or Vista PC.

I know this all sounds clumsy, but it's one of the few viable options for Windows XP users who want to upgrade to Windows 8 at a later date.

Windows 8 has certainly garnered mixed reviews at best, especially among PC users. Many people might want to steer clear of Microsoft's latest OS. But you never know what the future may hold.

At some point, you may decide you want Windows 8. And then you'll be happy you spent only$39.99 for the upgrade rather having to cough up a hefty $119.99 or $199.99.

Updated 2/6 9:30 a.m. PT to note that registration for the $14.99 offer is open until February 28.

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