Google Talk is the instant messaging client of Google. It is a lightweight application so it would not exert too much pressure on your local computer. However, like all Google applications, Google Talk can be accessed and used using your web browser.
There are three ways how you can use Google Talk. First, you can instantly use Talk service via your Gmail account. When you access Gmail, a GTalk chat tool will be available for you. Just use this to start chatting with your friends.
Second, you can simply use a web based Gmail client. You can get client apps from Google or from third party developers. You don’t have to download the Google Talk application. You can chat and call your friends through your browser.
Lastly, you can also download a standalone Google Talk client and install it on your computer. Use it just like any IM client to chat or make an Internet call.
The drawback of Google Talk is you cannot connect with friends using IM services of different networks. However, you can easily hack Google Talk to connect it with other IM services such as Yahoo, ICQ, or MSN.
To make the hack, simply connect your Google Talk to any Jabber server. Jabber is an open source IM service that provides client and server applications. There are lots of Jabber server applications which you can use for your local network or via the Internet.
Once you connect Gtalk to Jabber you can now select another IM service from Jabber to transport Talk to another service. You can now use Google Talk to communicate with friends on other networks.