Before sanding your floor, remember that the better equipment you use, the more chance you have of doing a good job,

I see far too many people ruining there floors with drum sanders, Drum sanders really should no longer exist, these are the sanders that are normally available at your local machine hire centre, they use sheets of sandpaper that are attached to a clamp and rolled around the roller and inserted into the other side of the clamp and screwed down. These are lightweight machines, Hiretech produce a type in the UK, I really don't know why they still produce these for the hire industry as they really are impossible to use, they are too light and bounce around the floor leaving chatter marks when the clamp between the sanding machine hits the wood, believe me its so worth finding a specialised hire shop that will hire you an 8 or 10 inch belt floor sander, Belt sanders have an endless belt that slips over a roller and drum and a clutch to lift the drum up and down, with a little practice you will find these are so much easier to use, use less sandpaper because the belts rarely tear, they will also save you having to countersink all nails as a belt sander will simply polish all the heads as it goes

Just put out a search on Google or Yahoo for floor sander hire and you should get half a dozen company's offering these types of machines,
I did this search a few minutes ago and was appalled to see HSS advertising there really poor hiretech drum sanders, so remember DO NOT Hire a Drum sander, you want a belt sander from a company such as Lagla, Bona, Clarke,Frank, Universal, Kunzle and Tasin just make sure the Sander you hire has a continuos 8 or 10 inch belt and a clutch, then you may even make a good job of sanding your floor, Im sure these drum machines are targeted at the DIY Market, so the end user can't actually do a good job and use many expensive sandpapers supplied by the hire shop making the bad job, I decided to post this due to too many jobs i have gone and put right because of these machines.
You have been warned.