Multiple Google Talk.
You can run multiple Google Talks with diffrent Usernames on the same system at a same time.Just follow the below method.
1) Create a Shortcut on ur Desktop.
2) In the field 'type the location of the item' paste the following source...
c:\program files\google\google talk\googletalk.exe" /nomutex
3)If this loction doesn't work, then locate manually by clicking on browse option. Then go to c: -> program file -> google-> google talk->googletalk.exe and then paste /nomutex in the end of manually located source.