When using a parameter query, is there a way to hide the "Enter a Parameter Value" on top of the dialog box"?

Make a popup form that looks like a parameter box, but refer to that text field instead of an actual parameter. You can also get several parameters in one form that way.

To expand a bit on David's explanation you would use code like this in the Criteria field of your query instead of what you have there now -

[Forms]![YourFormName]![NameOfControlWithCritera]