Almost a year after the release of Windows 8, Microsoft today released the first major upgrade to its operating system, Windows 8.1.

Starting today, those with Windows 8 machines can upgrade to Windows 8.1 for free via the Windows Store. The update hit at 7 a.m. ET this morning, and will be rolling out over the next 24 hours.

Those on Windows 7, Vista, or XP can visit the Windows upgrade page(Opens in a new window), which will detect whether or not your PC can handle Windows 8.1. On my PC running Windows 7 Professional service pack 1, I got a note that said “Windows 8.1 is coming soon,” so it appears the rollout is still in the works.

Starting on Friday, meanwhile, Microsoft stores will stock the packaged DVD version of Windows 8.1, while new PCs and tablets running Windows 8.1 will hit the market. This week alone, Lenovo introduced an 8-inch version of its Miix tablet, while Acer debuted its 8-inch Iconia W4 tablet, both of which sport Windows 8.1.

PCMag has been covering Windows 8.1 from the start. For the most comprehensive overview, be sure to check out our full review and the slideshow above. But our analysts have cooked up a number of specific guides to help you determine whether to make the leap to Windows 8.1 and how to get it done. Check out our full coverage below.

How-To Guides

• How to Install Windows 8.1
• How to Download Windows 8.1
• 5 Tips for Using Windows 8.1 Like a Boss
• How to Dual Boot Windows 8.1 and Windows 7
• The Top 6 New Features in Windows 8.1
• Hands On With Windows 8.1 Preview

News Stories

• Windows 8.1 to Include Revamped ‘Fresh Paint’ App
• Microsoft Details Windows 8.1 Pricing
• Windows 8.1 Officially Shipping to PC Makers
• Skype to Come Pre-Installed on Windows 8.1
• Q&A: Microsoft Talks Changes to SkyDrive in Windows 8.1
• IE11 Embraces Competitors’ Standards in Windows 8.1
• Microsoft Doubles Down With Bing for Windows 8.1
• Microsoft Tips Return of ‘Start’ Button in Windows 8.1
• Windows Blue Officially Dubbed Windows 8.1, Coming as Free Update

Opinion

• Is Windows 8.1 Windows 3.1 All Over Again?
• Windows 8.1 in the Enterprise
• Will Windows 8.1 Help Microsoft’s Push for Low-Cost Tablets and Laptops?