There are a few ways you can do this. With a popup form you can have a coloured box that grows during the calculation process... with your code I would do something like this..
VB Code:
  1. Do While MaxDD < Val(txtMaxDrawDown.Text)
  2.     Range("BC30").Select
  3.     ActiveCell.FormulaR1C1 = Risk
  4.     Worksheets("LBOP-New Capital p.a").Calculate
  5.     Range("BC25").Select
  6.     MaxDD = Range("BC25")
  7.         Risk = Risk - 0.00002
  8.     Progress = Val(txtMaxDrawDown.Text) - (MaxDD/Val(txtMaxDrawDown.Text))
  9.     boxProgress.Width = boxOriginal.Width - (boxOriginal.Width * Progress)
  10.     doevents
  11. Loop