Well, in order for you to get the full 54 MBPS your going to need a few things.
1) your going to need an 802.11g wireless ROUTER and ADAPTER. If the router is 802.11b the G card will lower its speed.
2) You will probably have to be very close. Although G devices have incredible range, its almost impossible to keep full speed once your going through a wall.
3) The speed difference really wont be noticeable unless your are transfering files through your network from PC to PC. Ill put money on the fact that your internet connection speed itsnt faster than 3-5Mbps, in which case anything above that on your network side is just gravy.
Hope that helps.