Everything "just worked" on the first boot, sound, net, video. It is silent (well we can't hear the fans spinning), and S3 and S5 acpi (sleep/standby) appear to work as well. They run a whole lot cooler than my custom 2.8 dual core in a old 4u rack mount chassis, so I can use them in my enclosed entertainment center.
Currently doing PXE with NFS for booting and ditched the HDD and Floppy to save power and reduce heat.
You can pick these up cheaply on ebay and used computer stores.