I actually don't know enough about Vista to answer that from personal experience, but it sounds like he's talking about the (known and resolved) typical-Microsoft-snafu NTLM thing. OSX uses Samba to handle SMB networking and Vista defaults to v2 of the NTLM security protocol, which is not supported in the version of Samba included in OSX 10.4. I did a quick search and found that the fix for this takes about 2 minutes of futzing with Vista settings:
http://www.builderau.com.au/blogs/co...tm?p=339270746
Also, your IT guy's English needs work. E.g., who are "they" in this case?