INFORIDS

How to multiple login in Gtalk chat simultaneously on Windows operating system? or

How to run multiple instances of GTalk with different Gmail accounts at the same time in Windows?

Solution considers Google Talk is already installed on your Windows. Following are the simple steps allowing you to login to multiple Google Talk accounts simultaneously.

1. Create Google Talk shortcut on your desktop, if its shortcut not already there on the desktop.
2. Now edit the shortcut by right clicking on the desktop icon and selecting Properties.
3. Now append /nomutex parameter at the end to the target property of the shortcut.
4.  The final string should become like "C:\program files\google\google talk\googletalk.exe" /nomutex
5. Click Ok and your are done.

Using this shortcut, launching multiple instances of Google Talk is possible, thereby allowing you to login to multiple Google Talk accounts simultaneously.

BONUS:

Like/nomutex switch, there are many others like /mailto, /factoryreset, /autostart, /forcestart and others. Give these also a try.