Installing New Network - No One Installed Administrator Accounts

I am installing a new network with all XP pro Sp2 PCs's. The issue is these PC's were all built prior to me setting up the network and no one installed the administrator accounts on any of them. The server box in Advanced server 2003 and I set up there accounts in active directory. Made the part of the server workgroup. Set up there share folders gave them permissions to the shares and I could not copy there files to the server. I get the message no rights or permissions contact the Administrator. I copied some test files to an
USB memory stick downloaded the to the server for testing purposes. We can see them from the desktop but we can't edit or save them. In the folder that the files were in I made sure that they were'nt read only and it still say's we don't have permissions to these files?