What is displayed by windows is the Link Speed, its not your true real time speed. Its the maximum possible speed for that connection that was negotiated when the connection was made. First since your router is a only 150 Mbps thats the best you can hope for. Having 300 Mbps network cards won't matter if the router only does 150 max. Also I've heard it said that if you have one G device on you N network all devices will fall back to G speeds. I have a DIR-655 set to N+G, bandwidth set to 20/40 auto. My PC with a DWA-552 shows 300 Mbps, even when my daughters G netbook is connected. I have noticed though that file transfer speeds are a lot lower when the netbook is on line. I would think if you have everything setup correctly in the router that you should be seeing a 150 Mbps link speed. Setting up encryption will affect the speed of your network, but it won't affect the indicated speed/link speed. I'm using WPA2 and my DWA-552 still reports 300 Mbps.