The Atheros range of chipsets are made by Atheros Communications. There is good support for them in linux through the MADWiFi project.
Some distros will support this out-of-the-box -- for example, in Ubuntu 5.04 and later, the packaged kernel and the linux-restricted-modules package provides support.
If your distro does not distribute non-Free drivers, you will need to install the driver from source.
You will need to download and compile an external module (not part of the vanilla linux kernel) from http://madwifi.sourceforge.net. But you should still have a kernel with CONFIG_NET_RADIO support (as described on the WirelessChipsets page). When this module is loaded, ifconfig -a should show a device called "ath0". Note that this driver also has a binary-only component which will taint your kernel.