Talking to myself here…
The problem was solved by scrapping the idea to have two network cards in that poor Thinkpad :-)
A switch Procurve 1810-24G av VLAN was the answer to all my needs.
For the curious:
Defined two VLAN:
[LAN] VLAN10 port: 1-22 Untagged, 23 excluded, 24 Tagged
[WAN] VLAN20 port: 23 untagged, 24 Tagged
Hardware:
Netgear CG3200 Cable Modem WAN-line (gigabit, NAT=off) into port 23 (100/10Mbit; Service provider is ComHem, Sweden, Stockholm)
Thinkpad T43 (gigabit internal nic, bge0) into port 24
fpSense NIC-config; VLAN:
[LAN] VLAN10; vlan0
[WAN] VLAN20; vlan1
Latest speed test with above config gives me: ~102 Mbit downstream and ~11 Mbit upstream.
Conclusion of above is as I see it that you shouldn't bother with multiple NICs in a PC. Go for one good gigabit NIC and leave the rest to the switch!
Brgs,
iorx