My Wireless USB Adapter is giving me slow download speed.

Hey guys i just brought this belkin wireless usb adapter N150 and it is giving me slow download speed. I checked on Speedtest.net and it gives me 0.20 mbps. It is not going to the max speed my max is 3.00 mbps it is not the wireless usb adapter because i checked on another computer and it went to the max 3.00 mbps and i putted it in the same location as my computer so than i realised that it was my computer that is giving slow download speed and it can't find much connections so i tryed it on another computer and it found heaps of connections any idea how to fix this? Plus the signal is excellent. I think there some thing inside my computer that is preventing it from finding lots of connections and making it have slow speed? Maybe it the hard drive im not sure . i just started using wireless i used cable before.

And the signal for my Wireless adapter is excellent