Cisco Systems has taken a key step to ensuring that spyware, viruses, and worms can't infiltrate a corporate network. Cisco announced that it <A HREF="http://news.zdnet.com/2100-1009_22-5898169.html?tag=zdnn.alert">has added software to its Ethernet switches</A> and wireless products that fit into its NAC (Network Admission Control) framework, which keeps networks safe by controlling which devices gain access to a network. Specifically, the NAC technology will be embedded in its switches and wireless gear. The new software will allow network access only to trusted end-point devices such as laptops, PCs, and PDAs.