J.
I have a Hoover Floor Mate. It uses a cleaning solution that it squirts on the floor, brushes to clean, and sucks up the dirt. I really like the squeaky-clean feeling on the floors - but our floors take a beating, with a dog, cat, and two active boys who like to play in the dirt and sandbox. A Scooba also sounds good! (the roomba that does the same thing.)
Get a dust mop and use it frequently - the biggest enemy of your floors is grit. If you have a sandbox, make sure you have a good entry mat. There are products you can buy for cleaning wood floors - I've seen a good selection in our hardware store, for some reason, but Target probably has some of the same stuff. I've heard people say that they avoid water, but I've never had a problem with using water as long as you don't leave the floors soaked. You don't want water laying on the floors. But in the dry winter, even using a moist mop, I've never found that to be an issue.
Oh - Murphy's Oil Soap is ok on polyurethane finishes as far as I know, but for people living in old apartments, it's a wax remover. I doubt that you have waxed floors, but just thought I'd mention that.