I recently purchased a home that was built in the 1950's. I decided to add room to the house and have begun the basement remodeling process. Here we are at the basement window. It too me and a friend approx. an hour to tear out the old steal frame window. We chisled around the outside and inside of the edge of the window. We then took a hacksaw and cut the bottom part of the frame in the middle. Then used a pry bar to tear out the sides and top. Then we chisled away as some of the cement that was in the way. Went to the local Home Depot and purchased a slider window for around $65. Purhased some weather striping, calk and a 8ft piece of pressure treated lumber (1X6) We cut to measurement and placed in window. Then put in some cement screws to hold wood frame in position. Placed window in frame and screwed to wood. A little calk here and a little calk there. Window is done. We did have to plane the side frame pices of wood down about a quarter of an inch to fit our window. All in all, this took us about 3 hours. Please remember to wear safety glasses when chisling away the cement. My friend was chisling and I thought I was far enough a way, but I caught a piece of cement in the eye and scrathed my eye.
Good luck to all.