I just went through the same thing. My house was built in 1908 with 50 double hung windows. I would make the following sugestions.
1.) remove the inside and outside window stops (vertical strips that keeps the window from falling out). You may need to remove the window stop between the inside and outside sashes. This piece is counter sunk into the window frame. If you break it during removal, new ones can be made very easily. Just rip a 1" X 4" to the correct with (usually 1/2").
2.) then I would recommend very strongly that you replace the sash weight ropes. Some houses of this vintage have small access pannels in the frame that can be removed for access to the sash weights. If not you will need to remove the facing for access. You can remove the inside or outside facing (your choice). Be sure to use cotton rope. Nylon stretches.
3.) Now that you have replaced the ropes, Iwould also recommend that yoou sand the edges of the window sashes (and the concealed sides of the window stops)and put a couple of coats of penetrating sealer(I used "Ducks Back") Do not use paint!! This will give you years of "stick-free" window movement.
4.) Now to your original question. It doesn't really matter how well you "adjust the window stops". The wind will still penetrate the openings. Very uncomfortable to the body in the winter and to your electric bill in the summer (if you live in the south or the oppisite if you live in the north). I've searched high and low for a solution. I finally found a plastic weather stripping (part no. "wwc-ws # 11BE")at www.dawsonsupply.com. you need to cut a saw kerf (a notch made with a table saw blade) down each edge and insert the plastic. when the window is re-inserted, the weather strip is invisible.
5.) After you weather stripp and put the sashes back in you are ready to adjust the stops. This is a very crude proceedure. You simply place the stops against the sashes and renail. Leave enough gap so the sash will move freely but not enough to let too much wind through. This process lends new meaning to "Sisyphean task". You can't have it both ways. Thats why I chose the weather striping route.
If you would like more details, email me ([email protected])and I will try to clarify.