ATG to Acquire Primus Knowledge Solutions, Inc.

Combination will create one of the largest online commerce and service software companies

CAMBRIDGE, Mass. and SEATTLE - August 10, 2004 - ATG (Art Technology Group, Inc., NASDAQ: ARTG) the software provider behind the Web`s richest customer experiences and Primus Knowledge Solutions, Inc. (NASDAQ: PKSI), an award-winning customer service software provider, today announced a definitive agreement for ATG to acquire Primus. Under the terms of the all stock deal, the transaction is valued at approximately $30 million to $33 million, based upon ATG`s closing stock price as of August 9, 2004. For the 12 month period ended June 30, 2004, the two companies had combined revenue of more than $90 million. Cost synergies between the two companies are expected to result in between $10 million and $15 million in annual savings beginning in 2005. The transaction is expected to close during the fourth quarter of 2004 and be accretive to ATG`s forecasted results for the full year 2005.

ATG`s industry-leading software for online commerce and marketing combined with Primus` award-winning customer service software solutions will create one of the industry`s largest online commerce and service software companies. The combination will produce the most complete consumer-facing platform to work seamlessly through Web, email, call center, and other channels.

"Companies want to market to, sell to and service their customers through a variety of channels and provide the most seamless, integrated experience for these customers," said Bob Burke, president and CEO of ATG. "Combining Primus` products and technical expertise with ATG creates an e-business powerhouse, with the breadth of technology and the critical mass that greatly enhances our ability to provide complete customer experience solutions across all channels."

ATG delivers a rich customer experience through integrated customer-facing marketing, selling and service applications. ATG software solutions include:
• The commerce application used by more high-end Web sites than any other
• The # 1 Scenario Personalization solution according to the Information Management Association. ATG Scenario Personalization [SM] is used by top performing Web sites including American Airlines, AT&T; Wireless, Fidelity Investments, InterContinental Hotels Group (ranked the Best International Hotel Site), Neiman Marcus, and Wells Fargo, to manage customer-facing business processes
• Marketing solutions that uniquely integrate email and Web interactions, ranked among the top four in the industry by Gartner
• Customer service technology that provides information that is more intelligent, personal and relevant

Primus is a recognized leader in self- and assisted-service technologies. Its software solutions include:
• The highest ranking solution in Web Self-Service suites from Gartner
• Advanced email response management technology ranked # 1 by Gartner
• Extensive knowledgebase and natural language processing search technology supporting call centers, help-desk staff, field service workers, wireless users and self-service sites
• Call center problem resolution technology integrated with major CRM suites such as Siebel, PeopleSoft and Remedy

"The combination of ATG`s commerce and marketing solutions with Primus` award-winning customer service and support technologies is a powerful and natural fit," said Michael Brochu, chairman, president and CEO of Primus. "This joint offering will provide enterprises with the industry`s most integrated customer experience solution to power their e-business initiatives and is a win-win for our customers, shareholders, employees, and partners."

The acquisition creates a number of synergies on both the top and bottom line. The opportunity to sell integrated commerce and service solutions into each company`s respective customer base provides ATG with significant revenue growth potential. On the expense side, the combination is expected to generate between $10 million and $15 million in annual savings beginning in 2005, through workforce synergies, facilities consolidation and the merger of accounting, legal and regulatory functions.

"Consolidation in the eService market is necessary as enterprises are looking for integrated multi-channel solutions that leverage all aspects of the customer service and support continuum," said Esteban Kolsky, senior research analyst, Gartner, Inc. "The combination of e-commerce and e-marketing with self- and assisted-service software solutions creates a necessary offering that enterprises today require to enhance the overall customer experience."

ABOUT ATG
ATG (Art Technology Group, Inc., NASDAQ: ARTG) delivers innovative software to help high-end consumer-facing companies create a richer, more adaptive interactive experience for their customers and partners online and via other channels. ATG has delivered category-leading e-business solutions to many of the world`s best-known brands including Best Buy, Kingfisher, Neiman Marcus, Target, Fidelity Investments, Friends Provident, Merrill Lynch, Wells Fargo, A&E; Networks, Warner Music, AT&T; Wireless, France Telecom, Philips, Procter & Gamble, Hewlett-Packard, American Airlines, InterContinental Hotels Group, US Army, and US Federal Aviation Administration. The company is headquartered in Cambridge, Massachusetts, with additional locations throughout North America, Europe, and Asia. For more information about ATG, please visit www.atg.com.

2004 Art Technology Group, Inc. ATG and Art Technology Group are registered trademarks of Art Technology Group, Inc., and Scenario Personalization is its service mark. All other product names, service marks, and trademarks mentioned herein are trademarks of their respective owners.

ABOUT PRIMUS KNOWLEDGE SOLUTIONS, INC.
Primus Knowledge Solutions (NASDAQ: PKSI) develops award-winning software that enables companies to provide a superior customer experience via contact centers, help desks, Web self-service, and electronic communication channels. Primus technology powers every interaction with knowledge to increase customer satisfaction and reduce operational costs. The company continues to receive industry accolades for its robust product platform, including a 2004 CRM Excellence Award and 2004 Users Choice Award for Primus? KnowledgeCenter, and "Strong Positive" ratings from Gartner, the leading provider of research and analysis on global IT, in both the Web Self-Service Gartner MarketScope for 1H04 and the ERMS Gartner MarketScope for 1H04. In 2003, Primus received the STAR Award for "Best Support Technology Vendor" from the Service & Support Professionals Association (SSPA), was recognized for its trend-setting products and named one of the "100 Companies that Matter in Knowledge Management" by KMWorld magazine, and received the CRM Excellence Award from the editors of Customer Interaction Solutions magazine. Global organizations such as Allied Irish Bank, The Boeing Company, CompuCom, EMC, Ericsson, Inc., Fujitsu Limited, Inc., IBM, HSBC, Orange, Motorola, 3Com, and T-Mobile rely on Primus technology to enhance their customer service and support initiatives. Visit www.primus.com for more information.