What speed is your wlan? In my experience, that is painfully slow indeed. Without encryption my transfer rates are about 20-35 mbps depending on where I am in my house. WPA slows the transfer down somewhat, but I still get around 15-20 mbps. TBH, I haven't had my wireless on for months, but I'm pretty sure those figures are accurate, and representative of most other speeds.
If you're mixing & matching vendors that could cause a problem as they never seem to 'play' well with each other.
Could be that your AP is situated next to something that is blocking signals - try moving it around and see if it makes a difference.
Sit closer to the AP and see if its faster than sat further away.
Failing that, just use a CAT5 cable like me
