Like stated, Wifi will always be free, at least from Verizon's side. There is no way they can charge you for that, it is not their network. However, unless you put on the data block, there is no way to make sure that you are only surfing the web with wifi-only, instead of the 3G network. Wifi takes priority, but it will automatically fall back to the 3G if the wifi connection is lost, even momentarily. In other words, if you plan on using the browser or email at all, i'd suggest you block data. There are other posts in these forums detailing how to do that, either from Verizon's side (via phone, online, or stores), or from the phone's side (hidden programming menu).