I would do the windows if you're going to live in the house. Besides the savings, they make the house a lot more comfortable with less fluctuation and moisture buildup. This caused issues for us with condensation dripping down the walls. Also, this could be a good thing to DIY and save some $$$. I found replacing windows one of the easier projects to do, and vinyl sliders cost around $200-$250 including the caulking, SS screws, interior trim, shims, paint, etc. If you can prepare all the openings yourself, hiring a helper to push the windows in and check level while you attach them helps too.