If you're in the states NewEgg has a nice feature allowing you to "drill down" by chipsets.
The amd motherboards in this link with 740G and 760G northbridges should work (ATI Radeon 2100 and 3000).
Newegg AMD motherboards as of 1Aug2011
I also asked and got a reply in this forum that Intel NM10 chipset has OpenBSD intel video support (but not FreeBSD). I have not tried an NM10 to verify but I have an older Atom 330 board that runs well. If you want a fan less low power solution this page has some options - The Atom 525 is dual core and 64bit.
NewEgg all-in-one-mobo as of 1Aug2011