Few people expected it, but Microsoft released the Windows 10 January Technical Preview bits at 9 a.m. PT on Friday. If you’ve been running the earlier tech previews, it’s one small step back and several giant steps forward. Stability reports are excellent -- I haven’t had any problems on a dozen machines.

If you don’t yet have your update and are willing to ride the beta roller coaster, sign up for the Insider Program, choose a suitable PC (or VM), and give it a whirl. Now that Microsoft’s servers have emerged from terminal meltdown, it should be relatively easy.

If you're trying to install the latest Windows 10 build on a Windows 8.1 PC, you may be greeted by the notice "Windows can't be installed because this PC uses a compressed operating system." I got it while trying to put build 9926 on a brand-new Asus Transformer.

The culprit? WIMboot. It's a Microsoft technology that squeezes Windows into a smaller footprint, so Windows can essentially boot from a compressed image. That's great for cheap PCs, but it doesn't play well with the Windows 10 installer. I haven't found any workaround.

As soon as you install build 9926, hurry over to the Update Center and get KB 3034229 installed. Click Start > Settings > Update & Recovery, Check for updates (if you don’t see KB 3034229 waiting for you), select the patch, and choose Restart Now.

Microsoft seems to be sending out its technical directives by Twitter, including a tweet by Gabe Aul suggesting you get KB 304229 installed.

If you aren’t yet using Twitter, install it and follow @GabeAul.

Before you start spelunking, be sure you check the Insider Hub. In the new (argh), fixed-size Start menu, it’s most likely below the taskbar, so scroll down the tiled part of the Start menu on the right, and click Insider Hub.

Click the link on the right for Known issues in Build 9926. That’s a list of known bugs, generally mirroring the list posted by MVP Andre Da Costa on the Answers Forum.