The "kernel" is the part of the operating system that runs programs and talks to the hardware. I'm not really sure what you're asking in the rest of the question.
in windows XP
Windows 7 does not have a kernel.
On Windows NT-based operating systems such as Windows XP, NTLDR is the file that is launched by the boot sector and is what loads the NT kernel. It can become corrupt for a number of reasons. For instance, this could be a sign that your hard drive is about to fail. When a hard drive is about to crash, it will sometimes boot into Windows while other times it will complain about corrupt files. It could also become corrupt because of a virus, bumping the PC, or maybe a bad shutdown of the PC.
No. Windows XP has it's own kernel and memory management system.
As Unix isn't any particular operating system, there is no distinct name for the kernel. Different versions of Unix may have vastly different kernel structures. The Linux kernel is called, well, the Linux kernel. The Vista kernel is a continuation of the "NT kernel" designed for Windows NT 3.1.
True
hardware mode
Yes.
shell, kernel
windows logo -Gabriel MGVR
NTLDR
NTLDR