Is it possible to boot from an external hard drive? I am assuming yes. In my scenario, I am running windows 7 through bootcamp on one of my two internal hard drives. The other hard drive is only for Mac.

How can I boot machine into windows using an external hard drive. My external hard drive is firewire 800

I am almost sure Windows 7 will NOT boot from an external in the home. Am I wrong?

To boot to another drive in a Mac is easy, if you 'clone' correctly . System Preferences->Startup Disk.

For bootable OS X I use the freeware/donationware Carbon Copy Cloner (http://www.bombich.com/). Check it out, you might like it.

i will be getting a eMac. i will be using it to install OS X on a external HDD and in return put that HDD into a mac with a failed CD Drive. i have no FireWire drives however i CAN get a USB to FireWire 400 adaptor using this and a gender changer i can turn any USB Drive into a FireWire Drive will this work the same as a FireWire enclosure as far as booting from external media goes?

Please show a link to a "USB to Firewire adapter".
You're likely looking at PCI cards, or multi-port hubs that have both USB and Firewire ports, which is not what you need, and won't do what you want (convert USB to Firewire).
I have never heard of a USB device that provides a Firewire output (changes USB to Firewire.) You may have the additional challenge of a USB 1.1 port, depending on which eMac you have, which your task then becomes impossible, even if a USB to Firewire adapter exists, as the USB 1.1 bus cannot possibly provide the bandwidth needed for a 400 Mbs Firewire. Can't work/doesn't exist.
You 'change' a USB-only drive to Firewire by removing the hard drive from the USB case, and installing in a case that includes a Firewire interface.
So, you need to get a Firewire external case.

this is the adaptor plug http://ecx.images-amazon.com/images/I/41I8UZg1T-L.jpg and this gender changer http://ecx.images-amazon.com/images/I/41Qor0be8oL.jpg i can plug any USB device into the gender changer and make it FireWire

Ah, OK, and it's just a couple of dollars.
At least you won't be wasting a lot of money.

I predict it won't work.

But - try it, and prove me wrong (I can always admit when I'm wrong - but I don't expect that :D )

why wouldnt it work?

USB and Firewire are completely different protocols
The Firewire cable has two active pairs for data.
USB has only one data pair.
That likely will restrict the connection (if it works at all) to FW100 or slower, not FW400
USB carries 5 volts at a low current for use by connected devices.
Firewire carries 30 volts, although I suspect that little adapter has no voltage changing capabilities, and would be only for those devices that use 4 pin firewire connectors that need no voltage through the connection, such as some cameras and other devices that don't need that. Not likely that little adapter can possibly work with a storage device like a hard drive.
But, like I said, it's only a couple of dollars, and maybe I'm completely wrong, so feel free to try it.

tip - if you are getting a few older Macs, a Firewire drive, especially an empty firewire case is a very handy device to have available.

yes i agree however the face i just spent 60 bucks not too long ago on a 3.5" USB HDD enclosure seems to be a waste

looking at external enclosures there is 1 question i have why do all Firewire drives have 2 FireWire ports? how do i know which of the two to use?

Two ports - one to use to attach to your computer, and the other would chain to another Firewire device.
Either port is good, and doesn't matter which one you use.
(Don't attach BOTH connections to and from the same device :D )

here is images providing PROOF that you can indeed boot a USB Hard Drive from a PowerPC eMac.

first image is the OPTION boot menu WITHOUT the USB Hard Drive connected the Second picture shows the same menu showing a Leopard Install partaion which is on the External USB Hard Drive. the unlabled parition is Ubuntu

That screenshot does not prove that you can successfully boot from a USB device. That screenshot merely proves that the USB drive appears to the system as a bootable device.

The real proof would be actually selecting that USB drive and successfully booting from it, which may or may not work.

It's like a car's speedometer going up to 180mph -- just because the dial reads "180" does NOT mean the car can actually do that. Just because the drive shows up does NOT mean the computer will boot successfully from it.

Try it, and if it works, then THAT would be proof.

it does boot but that is not something you can show in pictures. in my use of osx if its NOT bootable it WILL NOT show up in the boot list

it does boot but that is not something you can show in pictures. in my use of osx if its NOT bootable it WILL NOT show up in the boot list

The only reason it shows in the boot list is because the system sees a version of OSX installed on the volume. I see failing hard drives and volumes with completely incorrect versions of OSX show up in boot manager all the time that won't boot a machine.

ok so how to u propose i prove it boots i cant do that in pictures

Some PowerPC-based Macs will, in fact, boot from certain versions of OS X over USB. Your eMac is listed as not being able to, but it very well might with alternate bootloaders or more recent versions of OS X.

Just because your eMac does it doesn't mean that all eMacs, prior and after yours, will do the same. It's not a supported operation, and therefore, isn't recommened much in troubleshooting procedures.

Cool that yours does it. Are you using the standard Apple-supported BootX bootloader, or did one of your Linux installations install an alternate one?

Some PowerPC-based Macs will, in fact, boot from certain versions of OS X over USB. Your eMac is listed as not being able to, but it very well might with alternate bootloaders or more recent versions of OS X.

Just because your eMac does it doesn't mean that all eMacs, prior and after yours, will do the same. It's not a supported operation, and therefore, isn't recommened much in troubleshooting procedures.

Cool that yours does it. Are you using the standard Apple-supported BootX bootloader, or did one of your Linux installations install an alternate one?

i have no idea what bootloader i have i was able to boot from USB before and after i installed Ubuntu from what i have read Macs have been able to boot from USB since 10.4.2 somewhere around there

i have also read the macs have been USB bootable since the slot load iMac

i have also read...

When you say "I heard from..." or "I read that..." it's nice to provide a link to wherever you heard or read it from, like so:

http://hintsforums.macworld.com/archive/index.php/t-112196.html

This thread gives some insight as to what hardware can boot from USB, why it can or cannot boot from USB, the versions of Mac OS and Mac OS X that support USB booting, and how to work around it if you have a system or version of OS X that is difficult to boot from USB.

i dont link to the sites because i do not take note of them nor do i remember them

Then realize that when you say, "I read..." or "I heard..." without providing your source, people may find it hard to believe you, or they may take your suggestions with a rather large grain of salt.

Just a heads-up. Having such problems with organization and memory doesn't benefit anyone.

i have also read the macs have been USB bootable since the slot load iMac

Yes, an iMac that can boot natively with OS 9 can do so over USB. However, the boot process is super-slow, as USB 2.0 is not supported in OS 9, and most Macs that boot OS 9 will have USB 1.1 ports.
An eMac USB 2.0 model, for example, has USB 2.0 ports, can't boot natively to OS 9, and also can't boot to OS X over the USB bus, unless the arcane Open Firmware commands are entered, then providing the USB boot.
That would be the only option on most PPC Macs to boot OS X through USB.