Are you using the Sandberg Micro WiFi USB Dongle, like this one http://www.prisjakt.nu/produkt.php?p=822964?
And what hardware and image are you using?
I haven't seen anyone using a 150 Mbit/s dongle, only 54 Mbit/s and I read that it is based on the Realtek 8176 chipset.
/trasman