Enthusiasts interested in obtaining the Windows 8.1 Preview now have two options for doing so: The Windows Store-based installer, which is an interactive upgrade, and a new ISO download that will allow you to install the OS offline or as a clean install.
Which you choose is up to you, but there are a few things to consider.
First, if you’re using Windows RT, you have no choice: There’s no ISO downloader for Windows RT, so you will need to use the Windows Store installer and perform an in-place upgrade.
If you’re using Windows 8, you can use the Windows Store upgrader or download and then install from an ISO download. The Windows Store version is automatic: It will detect whether you have a 32-bit or 64-bit version of Windows 8 and deliver the correct version of the install. But if you want the ISO download, be sure to get the version(s) that are correct for your PC(s). You can find out whether you have a 32- or 64-bit version of Windows 8 using System properties. (Start Search, System in Settings, and then System. Under System, System type, you will see which it is.) You will also need to get the correct language version.
Third and most important: If you are going to use the Windows Store installer, be sure to create a Recovery disc or disk before proceeding. I wrote about this in Windows 8 Tip: Create Recovery Media, and it applies (especially) to Windows RT, where you’ll want to use USB-based media. Do not skip this step: If the installer hoses your system—as it did with my Surface RT—you will need the recovery media to get things back to normal.
Note, too, that the Windows 8.1 Preview won't (currently) install on some newer Atom-based PCs. Microsoft has a list on its web site, but it breaks down as follows: Lenovo ThinkPad Tablet 2, ASUS VivoTab TF810C, Samsung ATIV Smart PC, HP ElitePad 900, HP ENVY x2, Fujitsu ARROWS Tab. The firm says to visit the web site periodically as support for these systems will be added during the Preview time period.
Ready to roll? Here are the download links.
Windows Store installer
Visit the Windows 8.1 Preview web site with Windows 8 (any version) or Windows RT, click Get It Now and follow the steps. I’ll be writing up my experience using this process with Windows RT soon, but it’s pretty straightforward: You run a small installer and then visit the Windows Store to download the update (2+ GB depending on your OS) and the install from there.
Microsoft has made ISO downloads for the 32-bit and 64-bit versions of Windows 8. These can be transformed into bootable disc- or USB-based media from which you can perform a clean install of Windows 8.1 or an upgrade from Windows 8 to Windows 8.1
Visit the Download Windows 8.1 Preview page to get the ISO downloads in a variety of languages. The 32-bit versions are roughly 2.5 GB big, while the 64-bit versions are 3.2 GB. You’ll also want to make note of the product key, NTTX3-RV7VB-T7X7F-WQYYY-9Y92F, which you’ll need during Setup. Windows 8 can burn the ISO to disc, but you should also consider grabbing Microsoft’s free Windows 7 USB/DVD download tool, which can make either USB- or disc-based install media from the ISO file.