Here's the FAQ from Nelvana.com. The original is located at
http://www.nelvana.com/cardcaptors/html/faq.pl as of June 20, 2000 
Frequently Asked Questions 
3. What name changes have been made to the characters from the original
Japanese series? 
The following is a list of character name changes: 
Sakura Avalon was originally Sakura Kinomoto Li Showron was originally
Shaolan Li 
Keroberos (Kero)is unchanged 
Madison Taylor was orginally Tomoyo Daidoji Tori Avalon was originally
Kinomoto Toya Julian Star was originally Yukito Tsukishiro Meilin Rae
was originally Meilin Li 
Aiden Avalon was originally Fujitaka Kinomoto Natasha Avalon was
originally Nadesiko Kinomoto Layla Mackenzie was originally Kaho Mizuki
Rita was originally Rika 
Nikki was originally Naoko
Chelsea was originally Chiharu
Zachary was originally Takashi 
4. Why did you change the names of some of the characters from the
original Japanese version? 
Cardcaptors is directed at an English-speaking audience. Many fans are
children. Some of the original character names are difficult for
English-speaking children to pronounce. The new character names are as
similar to the original as possible while at the same time allowing
children to identify with the characters and ensuring the names are
memorable and simple.