Hi J.,
We just did this like 4 months ago.
We first took up all the carpet and then we got all the padding out, you need to get all the trim up (not the base board part but the rounded one) pull all nails and staples out of the floor. A pair of pliers works god for the staples and a hammer for the nails. After you do this you can get the stains out by sanding the floor down to new way, it's the easiest. You can rent a florr sander at Home depot. I can't remember how much it is to rent it exactly but it was like $300 for us to do our whole house and we rented it for the weekend. They will give you the sand paper and things needed. Son once you get everything sanded to new floor (You have to sand down with certain grit sandpaper) then we put wood filler in (our house is like 60 years old) it fills the gaps in between the wood slats. You put this on and let it dry then you have to said it down once you have all of this sanded down you can then Stain (sp?)(we used Minwax and natural). Put as many coats as you think are needed. I do home child care and have 4 childen and a yellow lab so we have high traffice everywhere, lol. We have done 6 coats so far and we need it again. After you get this done and it's dry (it will say how long it needs to dry on the can) Then you're last step is polyurethane everywhere (sealer) and you can't walk on this for a certain number of hours.
Couple of tips and notes.
* get all kids and animals out of the house see if the can stay the night at neighbors etc
*plan on dust being everywhere
*plan on eating out
open all windows and doors try to let as much dust out as you can, take a fan and have it blowing out of the house.
*When you stain and polyurathane plan on not walking on the floor if you can stay at a family members house at night that way you don't have to walk on it(depending on which rooms you are doing and how your floor plan is.
*It is well worth the money to rent the machine from Home depot.
*Also I haven't found something that I really like to clean the floor yet. I have used the Halloway house Quick shine and the finisher it seemed to strip the polyurathane. Murphy's oil soap is ok but it only stays shiny for a few hours. So for now we just use warm water and use murphy's every couple of weeks.
Let me know if I can help you or give you more info.