If your internet connection speed is of the order of 5 or 6 mbs it is not really relevant whether your router can connect at 54 or 108 mbs in effect both are many times faster than your internet connection and so will not make any difference to the speed of your internet connection. I fou have a two or three computers and maybe a printer connected to your network then the faster router would make a difference to any data transfers you made between them.
Douglas Cheney 