The following nice article was just updated to also cover Windows XP and Windows Server 2003:

http://www.sysinternals.com/ntw2k/info/ntdll.shtml

While we're on the topic, this book has been updated too and is due to be republished on Dec 8th
http://www.sysinternals.com/windowsinternals.shtml

And there's already a whole lot of begging on some forums for this to be warez as soon as possible. Some people just have no shame.

Regards,