Sample size for a one sample t-test

This [attachment:onesamp.xls spreadsheet] computes the total sample size for a one sample t-test with given power.

This can also be done using this [http://www.stat.ubc.ca/~rollin/stats/ssize/n1.html on-line calculator.] Both these programs use the more liberal normal quantiles as opposed to t quantiles for sample size evaluation.