Leopard DVD Boot failure question

I purchased Leopard for our iMac G5 (2.0 GHz PPC, the Ambient Light
Sensor model just before the built-in iSight camera models came out).
When I let it restart on request, it wouldn't boot. It got to a gray
screen and made extensive disk access sounds, but never booted, instead
spending nearly 30 minutes with a color wheel.

I subsequently tried booting from it the old-fashioned way, by simply
pressing the 'C' key with it in the drive during restart. Same deal.

Before concluding that I have received a defective DVD, it occurs to me
to wonder about something, however. The minimum system requirements say
512MB of memory, and this system has only 256MB. Would the install DVD
fail to boot if there's insufficient memory? Or is it more likely that
I have in fact received bad media?

I've ordered 1GB of memory that will arrive early next week, so I'll be
able to find this out myself for certain then, but I thought I'd ask if
anyone knows for certain while I wait.

TIA,
= Steve =
--
Steve W. Jackson
Montgomery, Alabama
.