I would like to rephrase my previous fail post. It is true that Skype is usually not used for gaming, as a good connection is required for the host of a conference call. If one does have a good connection, the conference will have near perfect quality. Lag is usually very minimal. I'd don't like using TeamSpeak because of server inconsistency, as well as security issues. Ventrillo is okay, but lag is very common.
The main reason Skype is not used for gaming is that it would require exchanging of account names, setting up a conference, ect. It doesn't work for many types of gaming.
I read this post, and tried both services you tried, and I have to say, a little laggy. But, I don't have the best intranets, in the world, I'm just saying that Skype is sufficient for my uses. (BUT I'm getting better internet tomorrow.)