The simplest way would be to use the new (to 2007/2010) Form style called Split Form.
In Form Design View, you arrange the Fields in the way you want to see it, when viewing a single Record. With the Form itself selected, you then go to Properties - Format and set the Default View Property to Split Form.
All Records will then appear at the top of the Form in Datasheet View, and a single Record at the bottom of the Form. When you click on a Record in the Datasheet portion of the Form, the Record displayed at the bottom will move to that selected Record.
Note that while, by default, the Datasheet View portion appears at the top of the entire Form, you can change this, through the Properties, so that it appears at the bottom or even down the left or right hand side of the entire Form.
Linq ;0)>
The problem with making anything foolproof...is that fools are so darn ingenious!
All posts/responses based on Access 2003/2007