For each query server (a server running the Office SharePoint Server Search
service, and is configured to "serve search queries" only)
Run the command
stsadm.exe -o osearch propagationlocation <location> where <location> is the
desired file system path for the search index files.
It is safe to remove any shares which were created as a MOSS workaround,
such as a share at the root of the D:\ drive named D_.
If not ....
For an index server:
The Edit Shared Services Provider page
STSADM.exe -o editssp
For a query server
The Configure Office SharePoint Server Search service Settings
STSADM.exe -o osearch propagationlocation
After completing the index move operation, the old index files must be
manually deleted.
By default, the indexes are stored in the directory <system drive>:\Program
Files\Microsoft Office Servers\12.0\Data\Applications\<GUID>.
Delete all directories and files below Applications.