Can I rely on any retirement planning program? They often give quite different results.

Answer: You should not get misled into thinking that any retirement projection is an accurate representation of the future. Practically every assumption you make is subject to change--which is why it's important to keep in mind what happened to those who retired in 1965. (See www.analyzenow.com) That's why I recommend making a new analysis each year and staying within that new affordable spending calculation. What is most useful from an analysis is a comparison of one case with another to try and choose what may be the best course of action.