Unlike its reason for failing to talk to MS’ own Zune players, this seems to be down to Microsoft’s weirdest, newest version of NTLMv2 authentication protocol, which can be worked past by instructing Vista to use NTLM or LM when it’s available.
Otherwise, you can update all of your appliances and Linux boxes to SaMBa 3.0.23d or later, which does enough gymnastics to cope with the odder, newer NTLMv2 protocol. Then wait for MS to break it again. . .