Do you want to replace just the inside glass, or the entire window, including the frames and casings?
This is not an average diy job. If you do not have any previous experience or skill with the task, then it is best to call a window installation pro.
Flipturn is correct.
Flashing & insulation must be addressed at that time.
old houses typically will have wood rot at the window framing.
Get quotes & make sure they comply with your the energy codes, so that you can get a Federal Tax Credit.
I disagree with flipturn, replacing windows is fairly easy if you have some skill, especially if you have fairly standard sized windows. My home is 110 years old. All the windows were rotting, badly taken care of and definitely not energy efficient.
Quotes we got ranged gettin 10k to 27k. New vinyl, double hung jeldwen windows were between 100 and 150 each. We have 27 windows. It nade sense for us to try and do it ourselves, especially since we live in a tiny village and only paid 85k for our when we bought it.
It was labor intensive, especially having to remove the window weights and insulate the empty space, and you need make sure to caulk outside, too. But the cost savings was tremendous, and our energy bills went way down.
Reply to Dianacirce70:
Yes, the cost for any diy can save you money as opposed to hiring out.
However, I did say: if you do not have any previous experience or skill with replacing windows.
Linda did not specify how high the windows are, what size they are, how old they are, or what style (sash, etc.) they are.
I am not disputing that it is possible to learn new skills. With some diy projects, a less than professional finish is adequate. With windows however, much of the integrity of the rest of the house is at risk if they are not installed correctly.
If you are not physically capable of climbing up on a ladder, and hoisting heavy windows in place, or if you do not already have all the requisite tools and knowledge on how to use them in the right way, then I would recommend to call a pro. This should ensure that the job is completed properly.