[Samba] server string ignored by Windows 7?

I'm upgrading the desktops on my LAN from Windows XP to Windows 7 (x64 Ultimate, if that matters). The samba version is 3.5.6 on FreeBSD 8.1 amd64. I can successfully map the samba shares on both XP and 7, but while XP shows the expected description which includes the server string (for ex-

[Samba] Windows 7 .vhd The version does not support this version of the file format error

I searched the archives for this particular error message, and only found one match from a user doing backups from Windows Server 2008 R2. I'm running FreeBSD 7.2 with (initially) SAMBA 3.3.9 from the FreeBSD Ports Collection. I have a very simple config (included below). The client is