This paper presents i-CAD, a novel computer-aided design tool for intranets that support data-intensive multimedia applications. We have formulated the intranet design problem as a combined optimization problem, consisting of a network architecture design problem, server placement problem and file allocation problem. Concurrently i-CAD determines the network strategy, interconnection hardware required, number and locations of file servers, and the static file allocation. While many optimization approaches described in the literature involve abstract networks, i-CAD is technology-relative, designing a complete network architecture along with selected components, using a database of current network technologies along with their costs and performances. An evolutionary approach is used to search the design space for good solutions. The experimental results for several large (65 to 150 nodes) intranet architecture problems show the effectiveness of i-CAD in finding good designs in few minutes.