Internet Explorer 11 is set to deliver with Windows 8.1 when it publicly releases on October 18th, 2013. IE11 is an improved web browsing experience even over the year-old IE10, providing faster browsing, smoother video, and additional security features.
If you remember, customers clamored for IE10 to release for Windows 7, and despite several beta builds, it looked like Microsoft would be late on delivering the release. IE11 for Windows 7 is in full swing and looks to be released on or close to the Windows 8.1 public release.
Microsoft has made available a Release Preview version of Internet Explorer 11 for Windows 7 for those that would like to download, test, and try-out a mostly baked version.
It can be downloaded from the Microsoft Download site here: Internet Explorer 11 Release Preview for Windows 7
There's also a 64bit version here: Internet Explorer 11 Release Preview for Windows 7 64-bit Edition and Windows Server 2008 R2 64-bit Edition
There will be differences between IE11 for Windows 7 and IE11 for Windows 8.1. Mary Jo Foley has a list of 6 or so items that will be noticeably different between the different operating system versions. Read that here: Microsoft rolls out IE11 for Windows 7 consumer preview