I made sure C:\\Documents and Settings\\Me\\Local Settings\\Temp\\ was empty, uninstalled GDS, then reinstalled it. I haven't yet reinstalled GDExtreme or TweakGDS. It's been indexing about 14 hours and has completed a little over 555,000 files.
So far, everything is acting very nicely. The CPU load is staying low when it's not indexing, and it's not intrusive. I've got the Sidebar turned off an am using Konfabulator with the Calendar, Analog Clock, NOAA weather radar, Google News, Simple Monitor, and The Weather widgets and everything is behaving fine. There's almost nothing in ...\\Temp\\ but the indexing isn't complete. ...\\Local Settings\\Application Data\\Google\\Google Desktop\\ has about 2.4 GB of stuff at the moment. I still have 13 GB free on C:\\
I didn't do a lot with Copernic, but it seemed to be less friendly - system-response-wise - in indexing than GDS at the moment. I didn't care for the interface much either, but we'll have to see if I end up going back to it.
More sometime later if I have anything to add.
Cheers,
Scott.