Sure you can. It's actually not all that hard in XP Pro.
And, doing this will afford you the opportunity to learn - very well - network share permissions & priveledges.
The quick and dirty, if you want the shares to be locked down rather well:
- all of your client user accounts should have a 'strong' password
- you'll want the same accounts (matching username / password) to exist on the server
- Guest account disabled on the server
- the Everyone group should be removed from the share access list
- each account should be given explicit access to each share, and given the level of access that you want to grant. Do this for each share.
That's the basics. Feel free to ask questions as you progress on this.