In their efforts to 'innovate' (a.k.a. make it harder for people to use non-Microsoft products) it would appear that connecting to a Samba file server in Vista is not as easy as in prior versions of Windows. This BuilderAu post describes how to enable LM and NTLM authentication methods supported by Samba but disabled in Vista by default. It sounds like the Samba team are moving fast on getting Samba fully Vista compatible, unfortunately issues like this will effect NAS devices and servers not running the latest versions of Samba for a long time to come.