On most laptops, the wireless antennas are located in the lid. When you close the lid, you change the position and angle of those antennas in relation to the currently connected wireless router. As for whether it should drop that much, it depends on the environment and signal strength.
To build on cklaubur's comment, can you try re-orienting the laptop or closing the laptop by lifting the base to the screen which you keep at it's open angle? That will keep the antenna orientation stationary, eliminating signal loss. Alternatively, you can try turning your routers antenna or body 90 degrees after closing the laptop lid and see if speeds are maintained.
So I tried with the usb wireless adapter, and it is actually running faster when I close the lid, then with the lid opened. Downloading consistantly at 3.5 to 4 mB/s. In regards to the power management options, I am pretty knowledgeable and I already tired this. I went and even adjust the power down settings in the driver details.
Yeah but it is a pain. I would never buy another samsung product again. Their online chat support guys gave up in 5 minutes after the first solution didn't work. Their response was for me contact the network card manufactor and disconnected the chat. I found this extremely rude, and was wondering if they had at least contact information. So I fired up another chat. Respresentative comes on immediately and tells me we told you to contact the manufactor and disconnects the chat... That really pissed me off! Considering it wasn't a cheap laptop and is still under warranty