TOKYO, Nov. 27 - As more consumers begin surfing the Web and sending e-mail messages on cellphone and hand-held devices, along comes a new worry: worms and viruses spread via Internet-enabled handsets. The problem is still small, with only a few cases reported globally. But as operating systems in cellphones become standardized, hackers will probably begin focusing on vulnerabilities in those systems as they have with personal computers. And as cellphones and personal digital assistants connect to the Internet at ever faster speeds, more users will be able to download files with attachments - some of which may be infected....