Well, I have almost the same setup (2xSlack 1xWindows98) and it's really easy.
Just make sure that your slack machine has an entry in /etc/hosts with the IP address of your Windows machine.
Do the same for the Windows machine, the file should be in c:\windows\ and named lmhosts.
This may be a little tricky if you are using DHCP, since you need to write down the addresses assigned to each machine by your hardware firewall/router. On the other hand, DHCP will usually assign always the same IP address to the same PC, so it's just a matter of using it once.
Also make sure your firewalls are configured properly on each machine, so that they can 'talk' to each other and not reject every packet.
For Samba, read the documentation: 'apropos samba' is your friend, and also take a look at http://www.samba.org
this site has a lot of docs.
Especially this one :
Samba is essentially configured using /etc/rc.d/rc.samba and /etc/smb.conf, make sure you read both files before doing anything...
Hope this helps!