have you tried to connect to the Linux box from a Windoze client? See if you can connect to the shared resource with a UNC command (\\server\share, from Start > Run).
If you can connect, then it looks like your machine isn't being shown. Try to find the master browser on the network (I don't remember the command, something w/nmblookup -M I think.) I guess it could be that your nmbd daemon isn't running maybe. Or i could be wrong.
At any rate, if you can connect to the share via UNC, then you know everything is set up properly, you're just not advertising to the subnet for some reason (it seems to me)
I've been trying to get good at Samba. If you haven't checked it out yet, an excellent resource is the free "Using Linux" online book available from
www.samba.org >USA >books >Using Samba.