Google talk app for windows will stop working on 16th Feb 2015, is the message Google sent to all its Google talk app users in a chat window.

gmail: Google Talk app for Windows will stop working on 16 Feb. 2015. It is replaced by the new Hangouts Chrome app. Install the Hangouts app from http://goo.gl/yglfk6

And instead you can install Hangout app on your Chrome browser and continue using the great chatting / video calling / audio calling facilities.