Internet Explorer 11 is now out for Windows 7
 

Now IE11 comes to Windows 7! Download links for every single language here, and full downloads, too.

If your system is up-to-date with regard to Windows updates, it should be painless and just one restart away. (IE is a Windows component.)

Of course, there's the Inori Aizawa version that's not out yet... if you're interested in that, check the other thread.

Hm, will there be a version for (straight) Windows 8? I don't want to update to 8.1 until I know it won't break my computer.

Never.

Looks like 8.1 should be treated as a Service Pack as far as support as concerned.