For anyone using cifs on plan9. MS appear to have changed somthing in the ntlmv2 auth protocol that cifs uses by default which means aux/cifs will not connect to Vista machines (and windows 7 boxes I assume).
cifs will connect using ntlm auth (i.e. ntlm v1) which is less secure but still reasonable - if you are using it over the internet sewer then ssh may keep your feet clean. ntlm is selected using the -a option to cifs: aux/cifs -a ntlm VistMachine -Steve