pmidwest,
I've just created a model for you. It does exactly what you've described.
I'll provide a description of what I've done, but you might prefer to email me, and I'll send you the file via return email.
First, here's the code:
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Set Target = Range("A1"

If ActiveCell.Address <> Target.Address Then Exit Sub
If Target = 1 Then
Worksheets("Sheet1"

.Shapes("Picture 1"

.Select
Selection.Formula = "p_1"
Range("A1"

.Select
Exit Sub
ElseIf Target = 2 Then
Worksheets("Sheet1"

.Shapes("Picture 1"

.Select
Selection.Formula = "p_2"
Range("A1"

.Select
Exit Sub
End If
End Sub
Additional Steps Required:
1) Place your pictures on a separate sheet.
2) Assign the range names "p_1" and "p_2" to each of the pictures. IMPORTANT: These names need to be assigned to the cells (ranges) BEHIND each picture - NOT to the pictures themselves.
I hope this helps. Be sure to email me if you find that option easier.
Regards, ...Dale Watson dwatson@bsi.gov.mb.ca