http://www.google.com/support/talkgadget/bin/answer.py?answer=57684&top…
"How do I make a call?
You'll need to have your Google Talk client (the downloadable application) running in order to make calls from the gadget.
If your friend is available for voice calls, you can call them by clicking their name in your contact list, then clicking Call. This will launch an active call window in the downloadable client."
Ha úgy próbáltad, próbáld ki úgy is, hogy nem fut a letölthető, windowsos kliens.