Please download RT3290 PCIe here: http://www.ralinktech.com/en/04_support/support.php?sn=501 Right-click it and rename it from 2012_RT3290.xx.bz2 to 2012_RT3290.xx.tar.bz2. Then right-click it and select Extract Here. Open the folder that is created and go to os/linux and open the file config.mk with a text editor. Change HAS_NATIVE_WPA_SUPPLICANT_SUPPORT=n to HAS_NATIVE_WPA_SUPPLICANT_SUPPORT=y. Save and close the text editor. Now, with a temporary wired ethernet connection, open a terminal and do:
sudo su
apt-get install linux-headers-generic build-essential
cd Desktop/2012_RT3
Press Tab and the remainder will fill in automatically. Press Enter. Then do:
make
make install
modprobe rt3290sta
exit
Your wireless should now be working.