Donna - Chances are you have oil on those floors - are they very shiny? Very shiny floors are often a sign of oil - latexes aren't as shiny.
I would not sand the floors - there is likely to be lead there too. Lead dust can be a problem.
Make sure they are clean - alcohol works really well in cutting grease,dirt, and wax.
Home Depot has a new Glidden floor paint which is great! It is new to them - but has been around in other labels for years. I have used it many times - in my own old farmhouse too - and it works wonderfully.
I personally like the oil for interior floors - I like the look of a shiny floor - plus which you will get very good durability - and it will be close in look to what the house would have had originally.
ps you can call 1-800-Glidden or go to GliddenPaint.com for further advice