Pidgin is a chat program which lets you log in to accounts on multiple chat networks simultaneously. This means that you can be chatting with friends on MSN, talking to a friend on Google Talk, and sitting in a Yahoo chat room all at the same time.
You can access it from Applications -> Internet menu.
At first run it asks you add your accounts you can add you gtalk account through that.
Empathy , the default chat client, supports google talk.
Pidgin
You can access it from Applications -> Internet menu. At first run it asks you add your accounts you can add you gtalk account through that.
Kopete
For KDE desktop, Kopete is the default chat application, and supports GTalk.
Gtalk uses the jabber protocol, which any number of non-web clients can use. I for example use iChat on mac.
Or may you want to try this trick, it works almost equal to gtalk for windows.You can make audio/video calls also http://tutafuta.com/2011/05/25/how-to-use-gtalk-on-linux-or-mac/