Private Sub Button1_MouseEnter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.MouseEnter
PictureBox1.Image = My.Resources.(Your Resource Name For Image)
End Sub
Private Sub Button1_MouseEnter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.MouseEnter
Dim thePath As String = "C:\yourimage.jpg"
PictureBox1.Image = thePath
End Sub