It's been nearly 20 years since Duffield launched PeopleSoft to help bring mainframe-caliber human resources software to PC-based systems. Now Duffield has turned his attention to the new high-tech frontier: on-demand systems. Next month, Duffield hopes to launch his new company, <A HREF="http://news.zdnet.com/2100-3513_22-6062991.html?tag=zdnn.alert">Workday, an on-demand business applications company.</A> Sources said it will seek to create a new way to organize HR data and to make decisions, using the latest service-oriented architecture tools to link to existing software.