I bought a wireless -G USB adapter for my PC so I can connect it wirelessly to my modem. The modem itself is 4 meters away (tho there are 2 walls seperating it from my PC), and I have full connectivity. The problem is that when using wireless I only download at half the speed I get when using a UTP cable (around 1,2 mb/s when using wired and 650 kb/s when using wireless). I have the following setup:

Modem: Zyxel P260-2HW
Wireless adapter: Linksys WUSB54GC

Things I've tried/Cancelled out

- I don't have a microwave or any other electric device between my pc and the modem.

- I tried using no encryption/security, but no change.

- I have the latest firmware of my modem and the adapter.

Does anyone have any idea of what's causing the speed loss? I expected ~some loss in speed, but not this much. Any tips/experiences are welcome. Thanks.