Restricting Specific Dates In Any Given Month

This may be a two part question, I finally was able to build a calender contol to insert dates into a active cell, now what i am trying to do is be able to restrict the usage of certain dates. For instance, dates prior to the current date cannot be chosen, nor dates that fall on 29th, 30th and month depending the 31st. Is this possible? Its is being used to calculate amounts for certain days, for example the calender object places a date in Cell A1, which falls between 1st-28th, another column also has a date option, the date to be chosen cannot be before todays date, and cannot be after the 28th of any given month. Is there a way to restrict in the calender or would a if statement apply? OR would a more simple approach to use data validation? where as (A1=MM, B1=DD, C1=YY) so that D1=A1/B1/C1 ie. 07/22/09, so that when using D1 it would be a date format. which would be the start date and E1,F1,G1 for a new date, then use conditional formatting to restrict or prevent choosing dates before TODAY() for the second date colums, I know a message could be displayed for it if it is less then/prior to the current date, or should i have the data validation adjust (if at all possible)for the first set of date options?