Problem making a gateway from 5.1-RELEASE

Hey,

This isn't quite -CURRENT, but it's 5.1-RELEASE.

I'm trying to put together a typical nat/gateway box.  But I can't
seem to get both network cards to work at the same time.  I've tried
a 3com card, a realtek card, as well as the onboard sis chipset card.
One card always works, the other seems to work (it gets a DHCP addy)
but I can't ping or otherwise communicate via it.  Although it seems
to be communicating somehow, as the output of netstat show that it
sees the other machines chattering on its subnet.  Sometimes it's the
3com that works, other times it's the realtek, depending on which
devices are installed/enabled.  I don't see any interrupt conflicts.

Below is the dmesg from when the 3com and realtek were installed with
the onboard sis disabled.  Does anyone have any ideas as to what's
going on?  Is this a case of the hardware just being too cheap?

Copyright (c) 1992-2003 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
	The Regents of the University of California. All rights reserved.
FreeBSD 5.1-RELEASE #2: Sat Aug  2 07:46:12 GMT 2003
     root_at_proxy.novadental.com:/usr/obj/usr/src/sys/PROXY
Preloaded elf kernel "/boot/kernel/kernel" at 0xc03f9000.
Preloaded elf module "/boot/kernel/acpi.ko" at 0xc03f9244.
Timecounter "i8254"  frequency 1193182 Hz
Timecounter "TSC"  frequency 1693130944 Hz
CPU: Intel(R) Celeron(R) CPU 1.70GHz (1693.13-MHz 686-class CPU)
   Origin = "GenuineIntel"  Id = 0xf13  Stepping = 3
   Features=0x3febfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM>
real memory  = 100597760 (95 MB)
avail memory = 93331456 (89 MB)
Pentium Pro MTRR support enabled
npx0: <math processor> on motherboard
npx0: INT 16 interface
acpi0: <AWARD  AWRDACPI> on motherboard
pcibios: BIOS version 2.10
Using $PIR table, 6 entries at 0xc00fdc90
acpi0: power button is handled as a fixed feature programming model.
Timecounter "ACPI-fast"  frequency 3579545 Hz
acpi_timer0: <24-bit timer at 3.579545MHz> port 0x1008-0x100b on acpi0
acpi_cpu0: <CPU> on acpi0
acpi_tz0: <thermal zone> on acpi0
acpi_button0: <Power Button> on acpi0
pcib0: <ACPI Host-PCI bridge> port 0x10c0-0x10ff,0x1000-0x10bf,0x480-0x48f,0xcf8-0xcff on acpi0
pci0: <ACPI PCI bus> on pcib0
agp0: <SIS Generic host to PCI bridge> mem 0xe8000000-0xebffffff at device 0.0 on pci0
pcib1: <PCIBIOS PCI-PCI bridge> at device 1.0 on pci0
pci1: <PCI bus> on pcib1
pci1: <display, VGA> at device 0.0 (no driver attached)
isab0: <PCI-ISA bridge> at device 2.0 on pci0
isa0: <ISA bus> on isab0
atapci0: <SiS 96X UDMA133 controller> port 0x4000-0x400f,0x374-0x377,0x170-0x177,0x3f4-0x3f7,0x1f0-0x1f7 at device 2.5 on pci0
ata0: at 0x1f0 irq 14 on atapci0
ata1: at 0x170 irq 15 on atapci0
pci0: <multimedia, audio> at device 2.7 (no driver attached)
pci0: <serial bus, USB> at device 3.0 (no driver attached)
pci0: <serial bus, USB> at device 3.1 (no driver attached)
pci0: <serial bus, USB> at device 3.3 (no driver attached)
dc0: <3Com OfficeConnect 10/100B> port 0xe000-0xe0ff mem 0xed102000-0xed1023ff irq 5 at device 6.0 on pci0
dc0: Ethernet address: 00:04:75:b5:27:2c
miibus0: <MII bus> on dc0
ukphy0: <Generic IEEE 802.3u media interface> on miibus0
ukphy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
rl0: <RealTek 8139 10/100BaseTX> port 0xe400-0xe4ff mem 0xed104000-0xed1040ff irq 11 at device 8.0 on pci0
rl0: Realtek 8139B detected. Warning, this may be unstable in autoselect mode
rl0: Ethernet address: 00:c0:ca:14:03:eb
miibus1: <MII bus> on rl0
rlphy0: <RealTek internal media interface> on miibus1
rlphy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
fdc0: <Enhanced floppy controller (i82077, NE72065 or clone)> port 0x3f7,0x3f2-0x3f5 irq 6 drq 2 on acpi0
fdc0: FIFO enabled, 8 bytes threshold
fd0: <1440-KB 3.5" drive> on fdc0 drive 0
sio0 port 0x3f8-0x3ff irq 4 on acpi0
sio0: type 16550A
ppc0 port 0x778-0x77b,0x378-0x37f irq 7 drq 3 on acpi0
ppc0: SMC-like chipset (ECP/EPP/PS2/NIBBLE) in COMPATIBLE mode
ppc0: FIFO with 16/16/9 bytes threshold
ppbus0: <Parallel port bus> on ppc0
lpt0: <Printer> on ppbus0
lpt0: Interrupt-driven port
ppi0: <Parallel I/O> on ppbus0
atkbdc0: <Keyboard controller (i8042)> port 0x64,0x60 irq 1 on acpi0
atkbd0: <AT Keyboard> flags 0x1 irq 1 on atkbdc0
kbd0 at atkbd0
psm0: <PS/2 Mouse> irq 12 on atkbdc0
psm0: model IntelliMouse, device ID 3
orm0: <Option ROM> at iomem 0xc0000-0xc7fff on isa0
pmtimer0 on isa0
sc0: <System console> at flags 0x100 on isa0
sc0: VGA <16 virtual consoles, flags=0x300>
sio1: configured irq 3 not in bitmap of probed irqs 0
sio1: port may not be enabled
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on isa0
Timecounters tick every 10.000 msec
ipfw2 initialized, divert disabled, rule-based forwarding enabled, default to deny, logging unlimited
ad0: 38166MB <WDC WD400BB-00DEA0> [77545/16/63] at ata0-master UDMA100
acd0: CDROM <ATAPI CD-ROM 52XMax> at ata1-slave PIO4
Mounting root from ufs:/dev/ad0s1a