Routers that once just shifted data packets around the Internet now figure out what new item--Internet phones, a laptop, a PDA, possibly an appliance--is joining the network.

FORBES: What Makes Cisco Run

While McAfee's software may keep viruses from being passed between a handheld computer and corporate network, it doesn't prevent viruses from being delivered wirelessly to the PDA in the first place.

CNN: McAfee aims to shield networks from PDA viruses