According to the manual, you should be able to boot the Inspiron 580 from USB:
Changing Boot Sequence for the Current Boot
You can use this feature, for example, to tell the computer to boot from the CD drive so that you can run the Dell Diagnostics on the Drivers and Utilities media, but you want the computer to boot from the hard drive when the diagnostic tests are complete. You can also use this feature to restart your computer to a USB device such as a floppy drive, memory key, or CD-RW drive.
The Boot Device Menu appears, listing all available boot devices.
For example, if you are booting to a USB memory key, highlight USB Flash Device and press <Enter>.
NOTE: To boot to a USB device, the device must be bootable. To make sure your device is bootable, check the device documentation
Hi Ron, thanks for your reply.
In the past, I've tried changing the setup as described in the manual but the usb device does not show up as an available boot device. The device I want to boot from is an external hard drive. The physical device is of similar technology to the installed system hard drive, except of course that it is external and goes through some sort of usb interface. It looks like a typical hard drive to the windows file system. I'm not sure, however, how the bios can detect whether it is "bootable". I'll have to take a look at that.
The dell 580 manual uses interestingly different phrases when referring to a usb device. What I mean by this is that is says "...to tell the computer to boot FROM the CD drive " and "...want the computer to boot FROM the hard drive ", but is never says anything about booting FROM a usb device. Instead, it talks about " ...restart your computer TO a USB device " and "...If you are booting TO a USB device". I don't mean to critique the grammar, rather, I wonder if there is an intended distinction in using FROM instead of TO? What does it mean to boot TO a device as opposed to booting FROM a device? Do you have any idea?
Drives Larger than 8 GIGS may not Boot USB because the Bios routine may be expecting the partition to be FAT16.
If the partition on the drive is NOT active this may also be why it wont boot. I would suggest using the Pendrivelinux utility and Knoppix version 6.7 or higher.
Thanks to Ron and SpeedStep for your reply.
I re-booted and f12 now shows the usb drive as an option to boot from. I don't know what might have changed to cause that. Perhaps my memory of what I had tried before is faulty.
My next step is to create an image of the system drive to the usb drive and try to boot from it. It currently contains an old (XP) system image.
Just to summarize:
I was eventually able to create and boot from the external hard drive.
I believe the true cause of my problem was that the drive I wanted to boot from was not truly bootable. That is, it was not configured properly. It had nothing to do with being an external -- as opposed to an internal -- drive. Once I created the image of my system drive onto the usb drive as a bootable disk, I was able to boot from it.
When the external drive was not configured as bootable, it did not even appear as an option in the bios boot drive list. I jumped to the conclusion that the bios was not capable of booting from any usb drive; that conclusion was unfounded. As Mr. Stoeckman, my high school biology teacher, used to say: "Now Phillip, you should get your exercise in gym class. Don't go jumping to any conclusions in my class."
Thanks for all the replies.