VPN Authentication

VPN Server is running on a Windows XP Home Edition
computer.
VPN Client is running on a machine that happens to be
Windows XP Professional.

I am able to make a connection to the VPN Server machine,
but I cannot get past

the login screen. Neither of the computers is on a
domain. Thus, what am I

supposed to put for a domain name.

I've tried logging in with as administrator, leaving the
domain field blank, but

it won't let me in.

How does one authenticate when there is no domain on
either system?

Thanks.