Best NAS device

What is the best NAS device to integrate with a windows network? Any of them integrate with Homegroup or do you have to go with WHS?

I need more storage for windows media center and i don't want more hdd's spinning in living room and i would like to use green drives if possible since platter speed isn't of utmost importance for storing / retreiving movies but i find a lot of nas devices can't stand the green drives.

has anyone done nas with iscsi on windows with consumer level devices (higher end.. over GigE of course)