Floors with polyurethane finishes are extremely durable.
With just minimal care your floor will look beautiful for years to come. The key to preserving your floor is protecting its finish. Urethane finished floors require minimal care, but it is important that you provide regular maintenance. It is particularly important to remove grit from the floor before it can be ground into the finish. Sweep the floor regularly and vacuum at least weekly. Regardless of its finish your floor will quickly lose its luster if exposed to water. More serious damage from water is also possible, including warping and other problems. Never wet mop a hardwood floor or leave spills unattended for long periods of time. Clean up spills before they turn into stains or otherwise damage the finish. For stubborn, sticky spills a damp mop with an approved cleaner may be used. Refinishing (top coating) will only be necessary once the weekly care fails to restore the floor's shine. Of course, never apply a wax to a floor with a urethane finish.
Precautions / Care:
One of the biggest enemies to a hardwood floor's polyurethane finish coat is grit. Sand, dirt and fine particles (grit) will in time be tracked onto any floor surface by normal foot traffic from the exterior environment. When compressed under footwear, this grit will act as an abrasive agent. Over a prolonged period of time, this abrasiveness will dull urethane finishes, cause scuff marks, and eventually wear through the floors urethane coatings. To prevent this abrasive wearing from occurring, it is essential that this grit is removed from the hardwood floor surface when ever it is present. This is commonly a few times a week.
Sweep/dust mop your floors regularly. A good broom that features exploded tips to trap dust and dirt is best. Dust mops can also be helpful in keeping dirt, dust, and grit under control. Use of a Swifter™ or similar dry floor pad is very helpful for fast day to day cleaning. Vacuuming is also a recommended for grit/dirt removal. The use of a canister vacuum with a soft bristle suction attachment will do the job nicely. Never use an upright vacuum with beater bars. They can cause scratches and dents in your floor's finish and wood surface.
Newly Re-Finshed Hardwood Floor Care Guide.
Here is a good YouTube video on basic wood floor maitainence it's about 2 minutes long.