Hi All,
I have tried the following steps, and it works smoothly to open multiple instances of GTalk in Windows, hope this little contribution can help every one. Following are the steps:
Step 1 : Download GTalk from http://www.google.com/talk/intl/en-GB/ and install.
Step 2 : Create a shortcut file on desktop( if it is not there )
Step 3 : Right click on GTalk and open properties.
Step 3 : Right click on GTalk and open properties.
Step 4 : At the end of the "target" field put "/nomutex" (ex: "C:\Program Files\Google\Google Talk\googletalk.exe" /nomutex)

Step 5 : Click on Apply and Ok
Step 6 : Now Click on GTalk shortcut on desktop, login and Minimize it.
Step 7 : Now once again click on GTalk shortcut on desktop and it will open new instance of GTalk and you can login with another userId.
Step 7 : Now once again click on GTalk shortcut on desktop and it will open new instance of GTalk and you can login with another userId.
All The Best
Narasimha Raju. Naidu
INDIA
INDIA