I use pfSense 2.0-BETA5 x86-64 at home on an Intel Atom D525 and am extremely happy with it. It handles everything I want and more.
Definitely go with an Intel dual NIC if you end up with a *BSD platform. For WiFi if you have a Marvell PCImini-PCI card the mwl(4) drivers in FreeBSD allow for up to 32 access points and wireless client at the same time. Works very well. I wish it was updated to use some of the newer mini-PCI-E cards but that is still a little far off.
