I know this is a shot in the dark, but is there any reason why IPsec  
would not support an older Network Card? I have asked them to move  
the newer one to the WAN and the older one to the LAN, but wanted to  
know if anyone had success IPsec'ing with older NICs.

sis0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
	options=40<POLLING>
	inet  netmask 0xfffffff8 broadcast
	ether 00:40:f4:6b:3f:77
	media: Ethernet autoselect (10baseT/UTP)   <------- NIC in question  
getting the SAINFO error in the tunnel.
	status: active
xl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
	options=1<RXCSUM>
	inet  netmask 0xffffff00 broadcast
	ether 00:50:04:bc:c3:88
	media: Ethernet autoselect (100baseTX)
	status: active