So to clarify your post. Do you want to set up a domain and have your XP boxes connect or do you want to create your samba server to be part of the workgroup? If it is part of the workgroup you will be able to use XP home edition. For a domain, your workstations all need to run XP professional or 2000.
Assuming that you only want a workgroup, you can configure your samba server to have public shares that will not need the windows users to be logged on. This is not!!! normally recommended for security reasons. If a hacker gets through your wireless security or firewall, they have a ready made network storage place.
It is also possible to restrict some users to be able to access their own shares and this could be done by hiding (read not advertising) some of the shares.
In samba you create all the shares and then make visible the public ones. The remainder would be left as private and the users workstations would have the share mapped on each one. This works well with a person per computer per share. Just remember that if they move between computers, as happens at my place, they will be accessing different shares. Unless you have set up different windows user account on each workstation for them and store the drive mappings in their profile.
My advice is to first set up your samba server and create the public shares. Next experiment with the private ones and see how you go. Remember while doing this, keep backups of the data (if needed) and regularly backup your config files. Oh and google anything you have problems with. We have all hit the same walls at some stage.
Here are a couple of my reference url's
http://samba.org/samba/docs/man/Samba-HOWTO-Collection/ http://www.brennan.id.au/18-Samba.html
In most cases the How To s and walk through s will talk about user accounts and logon's as most of us tend to be paranoid about security (they do know where you live and they are out to get you). If your people are never going to log on to your Linux box, you will not need to create Linux accounts for them and you can have no passwords. Again, only and I stress only, if you trust your users and feel confident in your network security (or have nothing worth stealing)
As for the wins server, I have a simple view in that all it does is maintain a list of machine names and addresses. That will allow your windows boxes to find each other quicker. That is my simplistic view on WINS. Someone with more knowledge will correct my ignorance.