The document profile when applies to MS products is a two way street, ie
if a document is added to the portal and properties are allready there the
portal will read them. And if a property is added/updated this is fed back
to the document property.

Other files susc as PDF,GIF BMP etc do not have these properties and as
such are only stored in the WSS so when the file leaves the WSS the property
is left behined.