DELL 1510 N WLAN Mini card driver problem

Hello,

I have a problem with speed of my wirelles card. I have windows 7. When I first install the windows, the driver that have been instaled with windows give variable speed for network, 100-130 mbps. But real download speed is maximum 24 mbps. I instaled the latest driver from dell website for this card and and compatible with studio 1537 (my laptop) and now speed of the network droped to maximum 54 mbps, but real download speed remained at maximum 24 mbps. I have 100 mbps internet speed and I have this speed when I connect the cable directly to laptop.

I tried different drivers, all the same results. What should I do? How I know this card support 150 mbs, I don't see them.

Thank you