This paper is published by CGI Group. One of the most debated subjects in the application development arena is that of the application server. Application servers store crucial and mission-critical e-commerce applications (B2C, B2B, B2E) and EAI, CRM and others. The question is whether to go for Microsoft or not, single or multi-vendor, single or multi-platform, multi-programming language or Java alone. In effect, the debate is whether to go with the new Microsoft .NET platform or Suns Java 2 Platform Enterprise Edition (J2EE), or perhaps a hybrid of the two.