I installed Windows 7 Ultimate 64 Bit in Unit "C" and Windows XP Pro SP3, in Unit "F". I tried 'n' times booting Windows XP and all attempts to answer is always the same. "Windows could not start because the following file is missing or corrupt: <Windows Root> \ System32 \ ntoskrnl.exe. Reinstall a copy of the above file." Thanks for the guidance.

At the suggestion of the moderator Makaveli213, I write in English, to acknowledge the guidance of Coolname007 "Master Magician". Topic: Steps to multi-boot with EasyBCD. Follow the instructions and solved the problem. I was about fifteen days searching on Microsoft and all world forums. You have the collective response more accurate and timely infrastructure Microsoft with their genius. In Colombia we say "heartfelt thanks" for the knowledge that NeoSmart Technologies is providing the surfer community.
Thank you melkin for the follow up. It is much appreciated to know we are helping others out when we can.