ok i will explain ,my setup as i did it. (but windows server offers better security)
1.First off, go to control panel and create accounts you want (yes give them passwords too).
2.Now go to folder options and disable
simple file sharing.
3.Now create the folder you want to share,and go to its properties.
On the "sharing" tab go to Permissions, and remove everything especially "
everyone".
Now simply add the users you created earlier.Give them ability to write and stuff but not FULL CONTROL.
You can also check the "security" tab for more advance stuff.
Now click ok and apply all changes.
This is what i did here, but i also changed some settings in the "security" tab, removing the administrator and unwanted users.
cheers
edit : i sometimes get difficulty mapping drives as it keeps prompting me for passwords but it may work in your case
if you didn't get that more can be found here
http://www.windowsecurity.com/articles/Share-Permissions.html