Can't log onto XPPro after creating Workgroup

I was following instructions to network my wife's XP Pro laptop and my
W98SE desktop and have possibly created a big problem. I was told to
make the Workgroup name on both computers the same and create a User on
my computer with the same name & password as my wife's.

So I looked to see the Workgroup name on hers, saw it was set to a
domain, changed it to a workgroup and gave it a name - and created the
same Workgroup name on mine, then created a User on mine with the same
username & password as hers. However after rebooting hers and doing
the Ctrl+Alt+Del to log on, the usual password for the user name was
rejected, and it said to check the username and domain were correct.
Yikes! I can't change it back from the Workgroup to the domain if I
can't get it logged in to Windows.

She's usually on a network at work, as you've probably gathered. Since
I changed it to a Workgroup, is there a different logical username? I
didn't set any new usernames or passwords. In Identity I did note the
full name of her computer and the domain name prior to making the
change, if that's any help.