NEW YORK (AP) -- Linux, the free operating system that's a perpetual underdog in the desktop market, will get another chance this holiday season at Wal-Mart Stores Inc. The chain was taking orders online Wednesday for a computer called the "Green gPC" that is made by Everex of Taiwan, costs $199 and runs Linux. It will be available in about 600 stores, as well as online, Wal-Mart said.