Try this:

1)Set the workgroup name in Application>Utilities>Directory Access

2) Set up sharing in the Sharing Control Panel

3) If you have upgraded to 10.2 (including reinstalls!) you must reset the password of the accounts for which sharing is required.

Sounds strange but this is essential - see quote below.

4) Add or edit accounts for which you whish to provide access and set the allow Windows access or similar, check box.

5) Note that netbios is not correctly implemented which means you may only browse the local workgroup but more significantly the machines visible are given their dns names not their netbios names. This means that if you are using DHCP you get lots of names which are meaningless or worse of your dns is not kept uptodate, you will see lots of very confusing names.

6) On no account install SSP (Samba Sharing Package) 2.5b2 or earlier which worked well on 10.1.5 but has a problem which will cause you not to be able to reboot and have to reinstall the OS. 2.5b3 available today may have cured this problem and this is beta software after all. When it works it will save having to edit the /etc/smb.config file.