Patti, the graphics that appear on the main page (the BoardIndex) are associated with the DS pilot that was made for the WB back in 2004 - and the current slideshow is celebrating that pilot's 10th anniversary. As with the '91 DS, the Greystone mansion served as Collinwood in the pilot, and as a background for the quotes that are being featured for the current scene in the pilot's script, I've picked a generic photo of Greystone's dining room because the scene takes place in that room.
As for whether the room is appropriate for the late 1700s, well, we don't honestly know when Collinwood was built in the pilot's DS universe. Though we are told in a future scene that the Collins family goes back "hundreds of years" and "for much of that time the Old House was their home" (whereas the Old House in the original series was the family's home for much less than one hundred years - more like thirty), so that remark alone
may change Collinwood's history in the pilot's DS universe.