Aon (US) and CSC Sign $600 Million IT Outsourcing Agreement

EL SEGUNDO, Calif., July 22, 2004 — Computer Sciences
Corporation (NYSE: CSC) announced today that it has signed a seven-year
contract worth approximately $600 million to provide Aon Corporation’s
(NYSE: AOC) U.S. operations with information technology (IT) infrastructure
support services.

Under the agreement, CSC will operate and manage Aon’s U.S.
telecommunications and data networks, desktop support, related help desk
services and various IT support functions. Aon will retain responsibility for
IT strategy and leadership, architecture and application development, and

“CSC is pleased to enter into this definitive agreement with Aon,” said
CSC Chairman and Chief Executive Officer Van B. Honeycutt. “CSC’s experience
in managing enterprise IT infrastructures and our understanding of the risk
management industry make us well suited to this role. We look forward to
helping Aon achieve its business goals.”

Approximately 600 Aon IT employees and contractors currently manage the
company’s technical infrastructure. Under the agreement, the majority are
expected to transition to CSC in late August.

About Aon

Aon Corporation ( is a leading provider of risk management
services, insurance and reinsurance brokerage, human capital and management
consulting, and specialty insurance underwriting. The company employs
approximately 53,000 professionals in its 600 offices in more than
120 countries. Backed by broad resources, industry knowledge and technical
expertise, Aon professionals help a wide range of clients develop effective
risk management and workforce productivity solutions.

About CSC

Founded in 1959, Computer Sciences Corporation is a leading global IT
services company. CSC’s mission is to provide customers in industry and
government with solutions crafted to meet their specific challenges and enable
them to profit from the advanced use of technology.

With approximately 90,000 employees, CSC provides innovative solutions for
customers around the world by applying leading technologies and CSC’s own
advanced capabilities. These include systems design and integration; IT and
business process outsourcing; applications software development; Web and
application hosting; and management consulting. Headquartered in El Segundo,
Calif., CSC reported revenue of $14.8 billion for the 12 months ended April 2,
2004. For more information, visit the company’s Web site at