Access 2000 Date Validation

Ok, so this is my problem.

First, I am building a database in Access and using a form built in Access to add records. I am trying to do a form level validation with two date fields, a start and an end date. I don’t want to force the validation at the table level as is causes a serious error, and I don’t want the client to have access to debuging the problem. I just want to have a msgbox prompt the client that the end date cannot be set to before the start date, and that the start date cannot be greater than today (ie now()). Hopefully someone can help me out!