I've been seeking on this forum.

I'm running the default samba version 2
The only thing I changed to get a VISTA client working is
modify a policy.

start | run | secpol.msc

Go to Local Policies | Security Options and find Network Security: LAN Manager authentcation level

Change settings from: SendNTLMv2 response only
to: NTLMv2 session security if negotiated