I bought the msi u160. The reason why the wifi card doesn't work is because the driver for this card (Ralink rt3090)are not in the kernel (or not detected) and they are not available in the "normal" repositories. The solution is to do:
* You will need a working wired connection while you do that.
1) Add these line into the file /etc/apt/sources.list
2) Update your sources with synaptic, apt-get or your your favorite package manager
### They are used with karmic instead of lucid because they are unavailable for lucid.
deb http://ppa.launchpad.net/markus-tisoft/rt3090/ubuntu karmic main
deb-src http://ppa.launchpad.net/markus-tisoft/rt3090/ubuntu karmic main
3) Install the package rt3090-dkms with your package manager.
sudo apt-get update
It should compile the driver without problem. It took about three minutes or less on mine.
sudo apt-get install rt3090-dkms
edit: I actually forgot to add the GPG key, just do: sudo add-apt-repository ppa:markus-tisoft/ppa
and do an update with your favorite package manager.