802.11n requires either no security or WPA2 (AES-CCMP). Original WPA (TKIP) and WEP are not supported. Make sure you configured your laptop to use WPA2. Either WPA2-personal (WPA2-PSK) or WPA2-Enterprise (WPA2 with 802.1X authentication) is acceptable.
802.11n also requires QoS (WMM/802.11e). Make sure you didn't disable that somewhere like in your driver's advanced properties.
Also note that some cheap wireless modules may only do 1x1 (1 spatial stream) 802.11n, and perhaps even with only 20MHz-wide channels, which has a max data rate of 72.2 megabits/sec, which isn't much higher than 802.11g's 54 megabits/sec max data rate.