Copy/Paste Restriction

We have just 4 PCs running Win XP SP2 in our small office. There’s NTFS on HDDs and the systems are networked through P2P. Because we are on a very tight budget, we cannot go for server/client network configuration. We have sort of designated one of the PCs as a repository of data. It is not used by anyone. Users have been granted permissions on specific files and folders on it and we are happy with data security as such. Except for one thing. And that’s the question I want to ask:
Can we prevent users from other machines to copy and paste files from this pseudo server to their own HDDs?
Any help suggestions would be appreciated.