Media for wireless g speeds - 22 mbps? 54 mbps 108 mpbs???

wireless g speeds - 22 mbps? 54 mbps 108 mpbs???

I have a question regarding wifi speeds. I am buying a wireless usb adapter for a new tivo and am looking for adapters.

Netgear has a 108 Mbps adater, but I was trying to do some research to find out if that is a marketing gimmick. I had thought that 54 Mbps was the maximum thruput, but I was reading on cnet that 802.11 g specs are:

20Mbps 150 feet range.

How can wifi g adapters give 54 or even 108 Mbps? Is this done through duplexing?

They say it's compatible with any wireless g device, so I don't think they're using any kind of proprietary boosting technology.

Any info would be helpful and appreciated.

Thanks,

Seth