When you install Windows XP SP1, you receive:

Setup Error
The <path>\Update.inf file is not correct.

If Cyptographic Services has NOT been started, you will receive this error.

To resolve this problem:

1. Open a CMD prompt.

2. Type net start "Cyptographic Services".

3. Install Windows XP SP1.

NOTE: See the fix from tip 6448 ยป 'Service Pack 1 Setup could not verify the integrity of the file'?