(help) Can you boot from an external cd/dvd drive?


I thought my problems were solved when the mac repair store stated they had left the optical drive unhooked. It worked for 2 days and broke. So I am very skeptical about taking my business to them (plus I've been waiting for a internal cd/dvd rw drive for over a week now to come in at their location).

My question is this---if I purchase an external cd/dvd rw combo, will I be able to boot from it? And how would i go about doing that?
Thank you
So much information, so little time :(

What model Mac do you have?
What make and model drive did you buy? (Firewire? USB?)
What operating system are you using?
If you hold down the C key on boot-up this should boot from your disk drives before any OS on a hard drive.

If you wanna open the disk drives first hold down the mouse button

Good luck
Sorry about that---G4 dual 867, mirrored doors. osx 10.3.9.
The external dvd drive is a firewire drive. I was able to run norton by booting from the external dvd drive and holding down the option key.
After I run disk repair in norton, my catalog b tree files keep coming up bad(the clump, etc).
I'm starting to get pretty worried that there is something deeply wrong with my g4. This is the 3rd hd Ive put in it.
I've just recently lost the ability to access my audio-midi setup.
Should I erase everything and reinstall?
Thanks for all the help!
More than likely, there is something deeply wrong with the Norton Systemworks that you tried. Most people at this site would warn you not to use Norton on any Mac using Panther and newer. It will cause the problems that you have mentioned. You may want to erase and start all over, but maybe a newer utility, such as DiskWarrior will get things going again without having to reinstall everything.
If you've been using Norton's on all three drives, that could be your problem.
Don't believe the errors it reports. Use Apple's Disk Utility from the OS CD. DiskWarrior would be my next choice.
I was just looking online at diskwarrior. if you recommend this I am willing to try it. This last year has been full of repeated problems with my mac, and I think that's about how long Ive been using norton systemworks.
What about antivirus protection---could I keep norton av without it causing problems, or is there an alternative.
Scrap Norton AV. Scrap anything that bares the "Symantec" or "Norton" badge. They're ALL bad, even if some people run them flawlessly.

Virex has just been updated to be compatible with Tiger. If you insist on using anti-virus software (which most people here will tell you is not necessary unless you're looking out for your Windows buddies), give Virex a try -- it's not the best (pretty much all anti-virus software sucks on Mac OS X, and for good reason -- the threat of viruses is almost non-existant), but it works.
I went and bought disk warrior. I ran it but was unable to retrieve or restore the midi setup. I'm getting ready to wipe the disk and start from scratch---without norton.
Wish me luck!
Is there any particular reason why an internal cd/dvd drive would be better than an external? I haven't had any problems with the lacie external dvd burner for booting programs and such (booted the osx disks as well).

I installed the major programs that I use yesterday---things seem to be running smoothly so far. I have disk warrior setup to noitufy me if there are any problems with the hardware.
If I lose this 3rd hd, I'm going to assume there is something that has been undiagnosed by the hw test cd, and by the service center. (It's making little whirrs, that I am not familiar with).

Thanks everybody, for the help.