On the other hand, if you've done your homework, then the whole process is as easy as a few clicks!
Sharing folders and files on Windows 2000 and XP requires that the users logged into their account and have an account on the other remote PC they are trying to access.
For example, let's assume I'm logged into an account named "Chris" on the Windows 2000 machine and you're logged into an account named "John" on the Windows XP machine.
At the same time, you've created a share on the XP machine and I need to access it from my Windows 2000 workstation. You'll need to also create an account for me on your XP machine using the same credentials (username/password) that I have on the Windows 2000 machine. The same situation exists if you need to access a share on my Windows 2000 machine -- I'll need to create a local account, which you'll use to log into and access my share.
When any of the two machines try to access each other's share, they will transparently authenticate (you won't be prompted for a username and password), and if the credentials are identical, then they will be able to obtain access to the folder or files without a problem.