Just so you know... although I can't really say I've done any more work on it... I still plan to finish it and no data has been lost AFAIK (I'm not sure where the backup CD from my last reformat is, but I know I've got one with LP4 on it)
Assuming the post on the old site was up to date:
Difficulty 1: 13 of 30 levels completed (11 100% optional, 2 100% required, 0 100% impossible)
Difficulty 2: 13 of 30 levels completed (10 100% optional, 1 100% required, 2 100% impossible)
Difficulty 3: 19 of 30 levels completed (8 100% optional, 7 100% required, 4 100% impossible)
Difficulty 4: 16 of 30 levels completed (2 100% optional, 7 100% required, 7 100% impossible)
Total: 61 of 120 levels completed (31 100% optional, 17 100% required, 13 100% impossible)