user profile change

I've got XP Pro. I've got a profile which logs me into my company's domain. I
have my username, password and the domain name. When i take my computer home
(laptop) I still use the same username, password and domain name to run my
computer. All of my documents are there. Email works, etc. Now, I know I'm
not actually logged in to the domain when I'm at home, but I can still use
this profile and everything looks the same, except I can't access the office
servers and intranet stuff (expected). Anyway, here is my problem... I don't
work for this company anymore and want to change the profile to not log in to
the domain, or at least try to, without losing all my other information. I'd
like to change the username and change the "join domain" options. When i did
this, it lost all my "my documents" stuff. I was able to do a restore back to
a previous date and it all recovered. Is there a way I can log in using this
profile and tell it i no longer want to join this domain? Can I log in using
my administrator log-in on the local machine and change the other profile?
Sorry for the very lengthy description. I appreciate any help.