Valve has announced that it will drop support for Windows XP and Vista systems during next year. After the 1st January 2019, Steam Client will not run anymore on those versions of Windows. In other words, your game library will be inaccessible until you upgrade to Windows 7 or newer.
According to Valve, the newest features in Steam rely on an embedded version of Google Chrome which isn't compatible with Windows XP and Vista. In addition, upcoming versions of Steam will require several security features that are available in Windows 7 or above. Furthermore, Valve will send several remainder during this year in order to invite users to update their PCs.
On the topic of the new Steam, Valve says that we will see a new chat that will offer new friends list, chat, and voice chat features. In other words, the upcoming chat client will be more flexible and modern. You will be able to create group chats, video call and much more.
Source:
Hexus