If Apple ever decides to let its Mac OS X operating system outside of its confines, the company can count Dell Inc. founder and Chairman Michael Dell as a possible customer. With the recent news that Apple plans to become a fellow customer of Intel Corp. for x86 processors, Dell has expressed interest in selling Mac OS X-based PCs, he said in an e-mail to Fortune published on the magazine’s Web site Thursday. “If Apple decides to open the Mac OS to others, we would be happy to offer it to our customers,” Dell wrote in the e-mail. A Dell...