I've been using Google Desktop for almost 2 years now. I needed a little more space on my hard drive, so I poked about with WinDirStat and found my Google Desktop index file was taking up 6.1 GB (on a 60 GB HD)! I've deleted it, so it has to start over, but how can I keep the index from getting so bloated in the future?
You could try using NTFS compression on the folder, but I'm not sure how much that will help. I remember doing it in the old days before Windows 7 came along, but I don't recall what compression level I got.