What is the advertised bandwidth of your "high speed extreme" internet? Unless it's over 10Mb, and actually delivers that, then even a g wireless network, or 10Mb wired connection, can handle it.
In other words, your LAN (and router) is probably never going to be a bottleneck.
I had a computer with an N wireless PCI card connected to an N router. I have FIOS internet at 15mbps. I switched to a hard wired 100mbps connection and the hardwired connection was noticeably better when surfing the internet. In theory, a G connection should work as well as wired and a N should work even better than wired, but in practice, I've found a wired connection is always better. I think a steady reliable 100mbps is much faster than a signal that can go up to 300mbps, but goes up and down like a yo-yo.
Well yes, wired is better than wireless in some ways. For instance, you could have interference with your wireless, or because of distance, you could get much less than the advertised bandwidth. Also probably the wireless has more overhead for error correction, and could be using more processor if you have encryption.
My point was more than "high speed internet" could be 768K DSL. Maybe the "extreme" part makes it 1.5Mb. In other words, what are the hard numbers, not the marketing words.