oh and BTW you have gtalk. It comes standard on the phone. It's the Talk app in your app drawer.
It's easier when people have the standalone computer application so that you can continue helping them even when their phone's are off (like when their flashing something).
I forget....I live on my phone anymore
and as for the warranty......it does void it, but you can unroot if you need to take it in so it's not a real big issue. Haven't heard of anyone getting denied yet.