Is PCI passthough all or nothing?

I'm coming back to vmWare ESXi after some time away on Citrix XenServer. The reason I'm coming back is because XenServer has poor PCI passthrough support. I want to passthrough two Conexant DVB-T cards to a VM running on ESXi. So I've installed ESXi vsn 5.1, but when I try to mark the DVB-T cards for PCI passthrough in vSphere Client, it forces me to tick ALL the PCI devices, which includes a dual-NIC PCI card. That results in those NICs being unavailable for VMs which is a showstopper for me.

1. Why does it force me to select all or none of the PCI devices?
2. Is there a way I can only mark the DVB-T cards for PCI passthough and therefore leave the PCI NICs available for the host?

My host is an HP HP Compaq 8200 Elite.