Rootkit revealer for Windows

For those of you who were unaware.. 'administrator' is not god.. when you work at the kernel level, you have light years more access than 'root' or 'administrator' would ever have.. because you can get the operating system to lie to any userland program.... its the ultimate level of privilege that you can obtain on a system..

Hmm, sorry for the 'stupid questions', but:
What is a rootkit?
What do you mean by "kernel level"?
What is a userland program?