Get seven of the Gigabyte HD2600Pro cards. Mine came with a breakout cable for component connection, plus you'll have HD acceleration (if needed) and the capability to go HDMI later. They're also passively cooled, so completely silent. It doesn't have any massive power requirements either.
Above all else, they're relatively cheap at about $75.
I don't even want to know what someone would need 7 HTPCs for. Unless there's a bunch of kids, that seems rediculous.
theHTPC.net