I just tried updating Archivarius' E-mail index - the one created using "custom mailboxes" with Outlook still running in the background and, as far as I can tell, no new messages were added after updating for 8 minutes. I deleted the index, closed Outlook, and recreated the index. Elapsed time? 6:23. This is a lot slower than dtSearch, but it works. I've deleted the index reliant on the OLE method (it was 12% updated after 17 minutes) and will simply rebuild the index with Outlook shutdown from now on...
Still loving dtSearch, but heeding Curt's advice!
Just to respond to Chris, who posted as I typed the above, Archivarius allows you to set up different indices as well, which is how I've got my installation set up. Agree about the price but am not so sure about the GUI - but I run XP in Classic mode, like Total Commander's GUI, and don't mind Archivarius text based previews...