LAKE BUENA VISTA, Fla. (Reuters) - Microsoft Corp. won't cut the price on its Windows operating system to compete with a $199 personal computer that runs rival operating software, the No. 1 software company's CEO said Wednesday. Walmart.com, the online shopping site of the nation's largest retailer Wal-Mart Inc., has been selling a $199 personal computer -- monitor and modem not included -- that runs the Lindows operating system. LindowsOS, from San Diego, California-based Lindows.com, is based on the Linux operating system, which is a free, open-source operating system that is increasingly being used by large corporations for back-end systems....