networking with different groups

Hi,

I have 6 Windows XP Pro computers on a network. They are under the
same workgroup. Sharing etc. works well.

3 of them are "management" computers, while other 3 are "terminals".
Right now, all shared folders are seen by each other. What I need is
the management should see all 6 computers while terminals should only
see themselves, which is 3.

What is the most cost-effective way to do it? (Please consider that
purchasing a hardware that will save time also cost-effective.)

I'm not an expert but I'm familiar with creating users, groups,
assigning users to groups, and setting permissions for those.

I appreciate your suggestions.