I was surfing the internet this morning and came across a very interesting social security calculator (at http://www.ssa.gov/OACT/anypia/download.html).

It (Calculator.msi) installs in windows and lets you look at hypotheticals, like mine -- what if I quit working at 55 instead of 60, etc.

It is a little tricky at first, but once you start putting information in it gets very easy to use and has a good help button.