Nick Grouf hopes to do for the Internet and Ford Motor Co. what Sam Walton did for price clubs. Grouf is only 31 and he heads PeoplePC, a San Francisco startup that didn't exist last summer. Even now, there are just 50 people on his payroll. But thanks to a fortuitous e-mail from Ford, PeoplePC is suddenly in the limelight and scrambling to fill computer orders for nearly 450,000 employees of Ford and Delta Airlines -- orders that two months ago seemed improbable even for a major company.