Hmmm. You said one of the NICs is an Intel - is that the non-onboard one? Is your onboard one a Realtek by any chance?
Yes, the on-board nic is a Realtek:
04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 06)
Subsystem: ASUSTeK Computer Inc. Device 8432
Flags: bus master, fast devsel, latency 0, IRQ 220
I/O ports at d800 [size=256]
Memory at fdfff000 (64-bit, prefetchable) [size=4K]
Memory at fdff8000 (64-bit, prefetchable) [size=16K]
Capabilities: <access denied>
Kernel driver in use: r8169
Kernel modules: r8169
And you've tried all possible combinations of swapping the labels in udev and swapping the cables (either physically or in web admin)?
I believe so.
Could it be that both your Jetway and HP laptop both have unrecognised NICs? I'm sure you're aware that Kubuntu 810 is somewhat long in the tooth now, so you do need to sometimes fart around with more modern hardware in order to get it working.
IPCop is even older, yet it happily hands out IPs to these devices. I know Kubuntu 8.10 is old, but IPCop runs a 2.4 kernel! LinuxMCE loads the kernel modules for the NICs no problem - they wouldn't come up otherwise, right? Also, I've used both NICs as the external interface - they got IPs from my external DHCP server without issue.
The PC I have LinuxMCE installed is new. Well, 6 months old now, but still...
I really hope I'm not missing something basic.