How to make bitmap project work on machines with 2GB ram ?

Dim cropFrm As Form
   Private Sub btnCrop_Click(sender As Object, e As EventArgs) Handles btnCrop.Click
       cropFrm = New Form2
       cropFrm.Show()
       cropFrm.TopMost = True
   End Sub

Private Sub Form2_MouseDown(sender As Object, e As MouseEventArgs) Handles MyBase.MouseDown
       StartX = e.X
       StartY = e.Y
   End Sub

   Private Sub Form2_MouseMove(sender As Object, e As MouseEventArgs) Handles MyBase.MouseMove
       If e.Button = Windows.Forms.MouseButtons.Left Then
           EndX = e.X
           EndY = e.Y
           wide = EndX - StartX
           high = EndY - StartY
           cropRt = New Rectangle((New Point(StartX, StartY)), New Size(wide, high))
           'Form1.Label1.Text = cropRt.ToString
           Refresh()

       End If
   End Sub
   Private Sub Form2_Paint(sender As Object, e As PaintEventArgs) Handles MyBase.Paint
       e.Graphics.DrawRectangle(New Pen(Color.Red, 2), cropRt)
   End Sub

   Private Sub CaptureCropRt()
       Dim ScreenPos As Point = Me.PointToScreen(New Point(0, 0))
       memoryImage = New Bitmap(wide, high)
       Dim s As Size = New Size(wide, high)
       Dim memoryGraphics As Graphics = Graphics.FromImage(memoryImage)
       memoryGraphics.CopyFromScreen(StartX + ScreenPos.X, StartY + ScreenPos.Y, 0, 0, s)
       memoryGraphics.Dispose()
       memoryImage.Dispose()
   End Sub