Finally i bought I replacement for my broken hard disk. I have bought a 320Gb Western Digital and reinstalled windows XP with some some software.
I still have no idea what was in that hard disk but for sure I have lost the light panel. I should have a backup in one of my memory stick.
Fortunately my photos are in the second hard disk and are safe (I have already done a new backup on a DVD).
I had a few minutes to continue working on the cutting of the panel. The idea of marking with a black pen the part to remove seems good but still not perfect.
I think I should remove the protection from the surface before coloring otherwise while using the dremel the transparent protection moves and it is difficult to have a clear picture of the border lines to cut out of the plexi.
I have to prepare a new mask and restarting with a new piece of plexi but with the new diamant tool I bought for the dremel the cutting seems much better then before.