First, I'd run the test at http://www.speedtest.net/ to see the actual connection speed. If low Is it possible you have connectede to the wrong router ?
Second, I'd use a third party too like InSSIDer from Metageek to analyze what connection you have, whether other routers are stepping on the same channel, what is the receive strangth of your router (in db - lower number is better), & make any needful adjustments.
With this information you should be able determine what is going on. Anything else is guesswork.
Fortunately I can connect all of my devices to a gigabit ethernet line (RJ-45) to get a good comparison between wired and WiFi.