That might be a rather unique situation though, if I needed constant
high-bandwidth on a LAN I'd get a more expensive Gbit adapter as soon
as a 2nd CPU/motherboard.

Ah, but therein lies the tradeoff: The adaptors which reduce interrupt
floods, via interrupt coallescing, do it at the expense of increased
latency. In some applications, that's alright. In others, it's a killer.

Of course, you can go even higher in cost to use switches which support
jumbo frames, but then you're speaking of such high dollar amounts that you
might as well just use SMP machines to begin with. : )

steve