Booting new computer on External CD-ROM drive..

[BstOnTheBrain]

I have a External DVD-RW/DVD-ROM, CD-W from my old computer that i used when the internal one went dead. So, for my new computer, i was just planning on using that one instead of buying an internal one and installing it. Do i need to have an internal one when i first boot my computer? Or would the external one not work without the right drivers installed...