Booting from External Drive

Just install OSX on one partition.

It's pretty simple - reboot from your installation disk, and do a fresh install of OS X on the partition you want. Then reboot from that partition (hold down the Opt key as you boot), and run any updates or particular setups you want.

You can set your Startup Disk from System Preferences, or use the Opt key while rebooting to temporarily switch the startup disk.

Matt

Hi. You could create a 'bootable' back-up clone of your working boot drive on a volume/partition of the firewire external HD; you could use CCC

http://www.bombich.com/software/ccc.html

or SuperDuper

http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html

You should disconnect any iSight during cloning with a firewire drive - and check several times that the cloned drive boots ok, and works ok.

Please post again if you need more details. Good Luck.

Unfortunately, booting OS X from a USB drive is not supported

http://docs.info.apple.com/article.html?artnum=106474

... which is why firewire is stressed, above.

Apparently, some of the Intel Macs will boot ok from USB; if you do a search at the Discussions top level on "boot from usb" or something similar, you may find guidance on how to do it for non-Intel. But you may wish to invest in a firewire drive for reliable booting - and keep the USB for storage.