AFAIK natively the 810 will only see files shared by a media server.
Yesterday ? I could only see a Folder called Shared Media and could play music, videos etc. with media player. And I could see Last night I went beserk at maemo, and may have installed an smb file sharing package.

Today I can see a folder called Shared Folders, it sees all my windoze shared folders (including admin shares) but won't let me descend into the directory structure beyond the share point. I can access my Linux (Ubunto) machine shares and access files.
And as I was typing this message I decided to reboot - now I can't see the Shared Folders (even my Linux box) anymore.
Only the Shared Media
DARN