Tiger on Quad Cores?

I just got a dual Quad-Core, 3GHz with 4gb ram.
I'd like to remove Leopard & install Tiger, however it won't boot up from
my 10.4.9 disk.
I've tried Command+C and holding Option key (it just reboots in to Lepoard).
Any suggestions?

Is this disc a full retail version or one that came with another Mac?

Is this a new (2008) Mac Pro?

New Macs generally only support the version of OS X they ship with.

Yes...new 2008 mac pro.
Install disks are apple originals.

In that case, you might not be able to do that.

This is from an Apple Knowledge Base article, Don't install older versions of Mac OS than what comes with your computer.