If you are interested in an independent calculation of your spendable income for the next twenty years, read this:
http://uk.news.yahoo.com/5/20090423/tbs-every-family-2-840-worse-off-by2017-327c223.html
http://uk.news.yahoo.com/5/20090423/tbs-every-family-2-840-worse-off-by2017-327c223.html