Talk and IM with your friends for free. Google Talk enables you to call or send instant messages to your friends for free–anytime, anywhere in the world. The Google Talk downloadable application for Windows offers many features for communicating with your friends and family.
Instant messaging — Chat with all of your Google Talk and Gmail contacts in real time.
Free PC-to-PC voice calls — You can talk to anyone else for free who’s online and has the Google Talk client.
Send and receive voicemails— If the person you’re calling isn’t available, you can leave a voicemail.
Unlimited file transfers — Send files to your contacts. There are no file size or bandwidth restrictions.
Gmail notifications on your desktop — When you’re signed into Google Talk, you’ll be notified of new messages in your Gmail inbox.
Requires Windows Vista/XP/2000.