What software can collect and analyze the sniffered traffic

Hi,
I have a cisco core switch 4006 with supervisor engine II in my network. But this device does not support netflow protocol. Now I have requirement to know the
traffic flow about each user in my network. This information can help me identify some abnormal traffic flow, such as network virus outbreak in specific computers. Now I prepare to setup port mirror in my core switch to sniffer the traffic flow through the core switch to the pix firewall. Can the Netflow Analyzer collect and analyze the traffic flow? If not, Do you have any other windows-platform software that can do it? Would you introduce it to me ? Thank you very much.