I just posted a dmesg from a SuperMicro motherboard with 8-core Intel Atom C2758.
Yeah, I've heard about that board. I think it's a tad overkill for our situation though :)
Depending on how you configure your disks the 8-core C2758 should be able to saturate a single gig-e nic.
Our system will be mainly a router rather than a file server, so I'm mostly concerned with how well it would handle network-to-network rather than disk-to-network.
Lemme put it a different way: a 500mhz P3 can handle pf on a saturated 100bt connection no sweat. I know Atoms are slower clock-for-clock, how do they compare (in general) and are there any OpenBSD specific concerns?