I'm assuming that you'll be selling your home? There was an article on the Realtor Mag. this month exactly on this issue. National Ave (and I'm quoating the mag) of cost recouped for siding replacement comes in at 88% and wood window replacements at 81%. However, depending on your area, the # can vary. These two items are at the top so if your area has been steady or appreciating, the # may be higher and it might be worth it. If your area is struggling a little or your budget is limited (and whose isn't, these days?), painting and a little landscaping might be the ticket. Ask your realtor that you've selected or if you're interviewing, ask about this. They'll know the right answer for your area. Good luck!