Finally I have found something I was really looking for... I have installed Rumbletalk plugin in my website and its really very nice application. Its fast, light, simple and deeply integrated with facebook and tweeter. Users can even login with their facebook and their facebook picture will be there on chat too. I really loved this feature.
One good feature is I did not need to host it on my site so I wont be facing issues from my hosting provider.
You can check a demo in my website:
Hope you guys will like it too like me....