Hello, I have Lightroom 2. I have a question about what catalog files I can delete. I have download backups whose file names look like this "Imported on Tuesday, June 15, 2010" and backup file names that look like this "2010-06-20 2109" that I have set to be created each time I open LR. I set up LR to automatically download both these backups to my internal hard drive and then I transfer them to a backed-up external drive. To save space on my internal hard drive, which of those LR backups do I absolutely need to keep and which can I toss? I assume I would need the most recent of both. I have plenty of room on my external drives but I'm the kind of person that would rather delete if I don't need them. I hate clutter. The download back-ups are larger files and I would be happy to get rid of all that I don't need. Also, My Lightroom 2 Catalog Previews.lrdata file is 3.53 GB. What does this file do for me? Do I need it? What about my Lightroom 2 Catalog.lrcat (111 MB)? Thanks!