foobar would let you maintain the file structure.
If your original file structure is based on tags then you could use tags in your Converter output string to create the structure, e.g.:
CODE
%artist%\%album%\%tracknumber% - %title%
If the two don't match exactly, and you want an exact match, then you would need to be using tokens like
%directoryname%, $filename% or %path%.
Try searching. My search returned
this relevant thread.
Edit: To be a little more specific: Use:
CODE
$replace(%path%,'X:\320kbps\','D:\Portable\192kbps\')
... as the "Output File Name" for single tracks (Converter dialogue), swapping 'X:\320kbps\' for the root of the source files, and 'D:\Portable\192kbps\' for the root for the destination files.