Can't create exchange email account

[Andy]

Hi,
I'm using outlook from Office XP and I can't seem to create
an exchange email account on one of Windows XP machines. I
entered the mail server name and then the user name and then
I clicked on "Check Name". The "Enter Password" window comes
up and no matter what I do, I can't get outlook to accept
the user name and password. It kept saying that I have
entered the wrong password.
I tried the same procedure on a different machine and it
worked.
I have a feeling that this might be a network setup problem
as outlook cannot access the exchange server. Can anyone help
me figure out what is wrong?
I'm running Windows XP Corporate Edition.

Thanks