A cached copy of your Domain Profile is stored on the Workstation. You should be able to logon to the Workstation when you are not connected to the Domain. If you have Policies enforced in GPO that remove the Cached Profile when you log off you will not be able to logon to the Workstation. Simple test is to log off the Domain and remove the Flylead, try to logon, if successful you are good to go. Do not save important Documents or Data in My Documents on the Workstation, create a seperate Folder to save in. Do not change the Workstation from the Domain to a Workgroup as you will lose the Cached Domain Profile. To get it back you will have to reconnect it to the Domain, and then logon.
I have not tried this method but it may work. Look for the Accepted Solution.
http://www.experts-exchange.com/OS/Microsoft_Operating_Systems/Windows/XP/Q_21771585.html#a16175936