unfortunately the bios in the dell doesn't have a delay on boot, and the USB external drive has no on/off switch.

have tried a few "workarounds" like going into the bios at boot and waiting for the drive to spin (doesn't work), set the bios to do a thorough test at boot to create a delay (doesn't work) and waiting for the hard drive to become active at the F12 boot select screen (also no good).

only way i can get it to work (and this only 50% of the time) is to switch on the laptop, let it autoboot into Vista, restart the laptop at the Vista login screen, hit F12 and select boot from external USB. a pain, and as i said, this only works 50% of the time, rest of the time i just get a "no boot sector on USB device" message instead of Darwin.