This howto is a setup for a domaincontroller server. This means you cannot connect to it with WinXP home, only WinXP professional, Win 2000 or win98 can connect to it. You cannot simply map a network drive as this is handled by the domaincontroller when you join the domain.
To join a domain with WinXP pro:
Go to MyComputer right click on Properties. Go to Change and click on Domain and enter the domain-name you want to join. When joining the domain, you will be first asked for the username that shall join the domain, its the user that you created in linux and added to samba. Then in the next step you have to enter the Administrator user "Administrator" and enter the password for the Administrator.