I'm actually considering one of those Atom setups for my pfsense box, berry. The system I have now is fine, but a P4 3.0 GHz with HT is really overpowering for a simple pfsense box.
For the folks who have an AM2+ system and want to jump to a hex core, keep in mind AMD isn't as limited to memory bandwidth like Intel CPUs seem to be. I'm seeing very little differences in hardware that use DDR2-800 / 1066 compared to DDR3-1066/1333.
I have a quad core, as you can see, and I have an i7-920 at work, and I'm hard pressed to find enough work for all 4 cores to do on my Phenom II, nevermind a work PC that does office tasks.
Quad is where the sweet spot is right now, but the hex cores are nice if you do a lot of rendering or photo manipulation work.