Are you capturing through BOB? Its been suggested in the past to disconnect BOB during capture and to use the MoBo firewire port rather than BOB's port. If you do not have a firewire port on the MoBo, I'd recommend that you remove all USB devices during capture PS 2 mice and keyboards are preferred in this case. Some fancy mice utilities soak up a ton of resources.
The usual software cautions, A/V off, and any active firewall. I do not normally enable any network devices, only on during program activation times..