Did you set up your amiga shares run on a user/password basis?
If so, Win98(and above) sends encrypted passwords, rather than the plain ones Win95 used.
I dunno about the newer Samba binaries that Olaf has just done, but the older ones only worked with plain passwords, so you needed to tweak the registry to get it to work.
Have a look at
AmigaSamba.org for more details.
DOH! just saw in your original post that you`ve visited that site..I must pay more attention !
BTW. can your amiga see its own shares ?