I have a desktop I am dual-booting with Windows/Ubuntu. In Windows, I'm getting around 8-12 mb/s, and in Ubuntu I'm currently getting ~.1 mb/s. I have a Belkin F7D1101 USB Wireless Adapter. I have the latest version of Ubuntu installed.
I'm not really sure what other information would be needed in order to help me, so comment if you need some info on my system.