Can I install FS9 on my (brand spanking new) external hard drive and have it run alongside my internal FS9 installation. Will the cfg. file in the C: drive double up or choke on itself?Also, and here's an odd one, is it possible, or even worthwhile, to remove all of the FS9 content you don't plan on using? I'm curious if I removed every bit of default scenery and planes I didn't want and just kept one area, would I get better performance?Thanks.

If your planning to run FS off of your external, I'm sure you could. But, it's not even worth it. An external connects through your firewire or usb, and eathier way, it's going to be very slow.

I did an install of FSX on an external, however I did not have it installed internally like you have FS9. Even though it was installed externally, the cfg file is still placed in your application data folder on your C drive, so I would think with FS9, it would be placed where your exsisting cfg file is, in the application data/ microsoft games folder, and possibily cause issues. I may be wrong, but this only makes sense to me. I hope this helped.

I run FS9 on a laptop. I have four Western Digital Passport Drives (1x 60GB, 2x 120GB and 1x 160GB). These are excellent little external drives that are powered via the USB connection. I have my FS9 installed on one of the 120GB drives with drive compression enabled, and it runs absolutely flawlessly. I see very little if any difference in loading times. To me it is a real advantage to have my entire FS installation on an external drive - whenever I want to fly I just plug the drive into a USB port and off I go.My FS9 installation has a *lot* of aircraft and scenery. What I've done is make a "Hangar" folder in my main aircraft folder, and I have moved all of my addon aircraft into this folder. I move each aircraft back into the main aircraft folder as and when I want to fly it. This means that FS doesn't have to load every single aircraft when it starts, just the one I want to fly! Likewise, I have all of my addon scenery airports disabled in the scenery library, and I just enable the ones that are relevant to the flight I want. This makes FS load up a lot faster as it doesn't have to load every single aircraft and scenery addon I have.I'm not too sure what installing FS9 twice on your system would do, as it places entries in your registry. Presumably if you installed FS for a second time it would overwrite the original registry entries with new ones pointing to your second istallation. This could be problematic if you want to install a third party addon into the first FS installation, and the FS9 registry enties point to the second FS9 installtion! Phew! Did that make any sense? I have seen a utility that allows you to edit or repair the FS9 registry entries.Bottom line: Running FS9 on an external drive? No problem at all, it's not slower, and the sky won't fall on your head. Istalling FS9 twice? Not so sure, it's definitely possible, but may cause some headaches when third party addon installers won't let you install into the FS installation you want.

Thanks for the replies. Much appreciated.The goal of the second install is madness and curiosity. I was wondering what would happen if I killed all scenery but Alaska and B.C. and had only one or two aircraft. Would this make for faster FPS or only faster load times. My machine runs FS9 very nicely with lots of add-ons, I was simply curious if the sim could be reduced in size to maximize performance in a given area.