With runtime folders on one of my systems at 27.9 gig and climbing I realized real quick that an external HD was going to be the only practical way to back it up. I also make sure that my individual pz3 scene files are backed over to CD-RWs immediately. Between complete backups if I lose everything on the HD I will at least have the pz3s after everything is rebuilt or reloaded. My pz3s change the most often, of course. So, I guess my advice is get an external HD and backup your pz3 scene files daily. I just went through my system last week and cleared away a few gigs of stuff I hadn't used in quite awhile. I learned that that should be at least a quarterly project. You'd be amazed at how much stuff just sits there never or rarely used. But I've always been a pack rat. ;-) Take care, be well, keep flying. casamerica