In reading your post I did some research on the spelling of the word
center/re. To be honest prior to your post I had never really given much
thought to the spelling of the word as it appears in “MS adCenter”.
In doing so I found this article that not only explains the reason for the
two spellings, it also states which one is more commonly used amongst all
countries.
I can only speak for myself being "French Canadian" I have
always spelled it "center".
You may find the article below as interesting as I did, and in reading it you may change your
view/opion on how the spelling of this word makes MS appear to other countries.
According to this article and many others I have read "center" is the more commonly used spelling.
Thank you,
Elle
http://en.wikipedia.org/wiki/American_and_British_English_spelling_differences