Microsoft placed a tool online that downloads an ISO file which can be used to then force an install of Windows 10. This update is free for Windows 7 and Windows 8.1 users.

Lots of users if not most have not upgraded just yet. And if you are an impatient person like yours truly, by using this tool that becomes a forced update. The ISO that is download is 3GB in size, you get an option to upgrade from the ISO or make an install USB which you can use for other computers as well.

Have a peek and download the tool here (I imagine the internet backbone will be under high load today after all).

BTW after installation if you need the latest GeForce compatible driver, download here. AMD is still pending but will be download automatically though Windows Update within Windows 10.

Windows 10 was this Wednesday in 190 countries and 111 languages. Microsoft promises a free upgrade to Windows 10 for Windows 7- and Windows 8.1 users under the condition that you upgrade within a year.

Update: I just updated our graphcis card test system. It installed fine. For those that wonder. Graphics perf seems about 99.98% the same.

Example, a GeForce GTX 980 Ti does 100 points more in the overall P scores opposed to Windows 8.1 at 15744 points. And thats including a dozen driver differences.
 

GTX 980 Ti on Windows 8.1

GTX 980 Ti on Windows 10