i havnt seen any bit of networking kit reach the speeds it "ought" to do
if your wireless speeds are on the slow side check you have the latest drivers for your card and firmware for ur router.
also (and its a pain i know) try older drivers for ur wireless card - sometimes stuff happens
Id also try knocking down the security bit by bit if its super fast under a different security system we will have to look at other options.
have a play and change stuff