Maintaining Integrity

I have been put in charge of a project with my company. This involves a hospital. There are 600 PCs (50 for med students, 200 in doctor’s offices, 20 in the OR’s to assist the surgeons in real-time, and the remaining are used by the admin staff). The network is a mostly switched, star-wired bus network using Ethernet 100BaseT. I need to identify the critical points of failure on this network and ways to eliminate them.