I finally made the plunge--I didn't want to mess up anything on my present computer so I bought a new computer (Asus P5GC-MX/1333 mother board) with a Hitachi 160 GB HD and an Optiarc DVD.
I've tried to install Ubuntu 7.10 and 8.04-- both with no success.
I keep getting a message "reboot and select proper boot device or insert boot medium in selected boot device and press any key...
My computer's setup reads as follows:
Primary master--not detected
Primary slave --not detected
3rd master--Hitachi HD
3rd slave---not detected
4th master not detected
4th slave-- optiarc DVD

My questions: is this configuration amenable to setting up an operaating system from the CD to the HD? What could be the reason for not being able to get ANYWHERE in the installation?
I've tried changing the configurations but all variations have been unsuccessful. Could the fault be in my Program discs? I dowloaded them from the Ubuntu site and think that it was done properly. Culd it be that my MoBo is not compatable with Linux (is there such a possibility?)

Thanks in advance for suggestions.

First of all, test that it's not the disc by inserting it into your working computer. If it boots fine, then the CD works and you've got a hardware issue. If not, chances are that the CD is defective and you should get a new one.

The next thing you want to check is your BIOS setup. You need to make sure that both the optical drive and the hard drive are listed as bootable, and that the optical drive has the highest priority. Then save your changes and try again.

OKAY John--I re-burned my setup disk at a slower speed than the first one I used. I then went over the BIOS and made minimal changes, checking that both disks were bootable and inserted my new CD.
Right now the system is in the process of checking out the disk, but I'm so excited that I am responding even before installation--just that I got this far is exciting.
I'll get back to you after the installation (assuming that all will go smoothly) and mark the thread as solved. But for the moment--a big thanks!

Now I can say THANKS up-front!
All went amazingly well and smoothly. The whole system has been set-up with minimal "interference" from me.
Of course, now that I finally have a Linux distro, I'm sure that you'll be bombarded with all sorts of additional questions from a first-time user.
They'll be coming slowly for a while now since my wife and I are hosting 9 grandchildren for what remains of their summer vacation. Cumputers will have to take second place (at least during the daytime hours).