Painting - painting windows

our new house has double-hung windows that have been painted & now are hard to open, or wont open. how can we fix this?

Very carefully!!

If necessarry take an utility knife and cut the paint along the window edge. Using a stiff putty knife work it in along the the track wiggling it back and forth to loosen the window. Don't rush opening the window, gently work the putty knife around at all points - both inside and outside if possible.
Once the window is free, working it up and down usually gets it working correctly again. In extreme cases you may need to sand/scrape some paint from the edges.

thanks for the info. after i get opening, i need to reglaze them. can you tell me what type of paint i need to use after glazing the windows?
Thanks,
Chris

Just so there is no misunderstanding, glazing is used on the ext sash to hold the panes of glass in. After removal of old/bad glazing, prime the raw wood, then glaze, prime when dry and then paint with your choice of exterior paint.

If you are repainting the interior side of the window be sure to scrape and sand all the areas that are causing them to stick. Then carefully repaint by not filling the edge where the window moves with paint. Shortly after drying be sure to work the windows up and down several times.

thanks, i knew glazing was for the outside. thanks for the inside painting tip