So after all my troubles trying to get Fedora 11 x86_64 kit installed and failing, I tried Kubuntu.
I prefer KDE desktop to Gnome, so went with the KDE Ubuntu 9.04 "Jaunty" version, Kubuntu. Ubuntu itself is Debian-based.
Took two tries, but the second try was the real thing, and within an hour the the 64-bit kit was installed, and fully working - including the DVD playback as well as audio.
Update: not that good, in the end. When I got new drives, and re-did the full install it failed to get audio working. Oh well, so these Linux distributions are not as good as Windows when it comes to multi-media support. Since I do not use audio, I am going to stick with Jaunty and will update the system again when the next release comes out.
First try:
The documentation on the Ubuntu pages is somewhat unclear. I knew I wanted LVM, and expected that the DVD iso image for desktop install would offer it. No mention is made of this on the Get Ubuntu pages. It does refer to something call "alternate" kit which is text-mode install for systems with small amounts of memory. So, went with the desktop kit. It is also not very clear that the "amd64" kit is for Core 2 Duo Intel processors also, in fact, some of the language might indicate that it is only for AMD CPUs, but that would be an incorrect reading. So, for Core 2 Duo, use amd64.
But overall, using the desktop kit was the wrong thing to do. Took an hour to install, discovered the problem with no LVM, so went back to web searches, and discovered (in not-so-easy to find places) that the alternate kit is the more powerful kit, and has much better control and many more options for the install.
Second try:
Now using the kubuntu-9.04-alternate-amd64.iso kit, started the install. Things to note: if you let the installer "Guide the partitioning", it will end up not what you want - it seemed to have installed the boot partition at the end of the disk, when it is far better to have this in the lower numbered cylinders (though that may not matter for the newer BIOSes). So, best option here is to select the "Manual" partitioning method. For my purposes, the following works fine:
Primary Partition#1 sda1 /boot ext3 100M
Primary Partition#2 sda2 /lvm logical volume group, which has
/ ext4 25G, swap 2.5G, /home ext4 rest. Left two 3G partitions unused - will be using them for creating kvm virtual machines.
The installer is text mode, so not as polished as the Fedora 11 installer. (But, Kubuntu installer worked, and Fedora installer didn't.)
A few more questions here and there, it also downloaded some packaged from the net during the install, and in under and hour, the system was up.
On logging in, was the amazing part - within minutes Kubuntu recommended the proprietary driver for Nvidia, which made the display look correct (1600x1200 mode).
And even more magically, the Update Notifier asked if packages for multi-media - from MPEG, to MP3, to Flash, to DVD, etc should be installed. Click the button, and it all was automatically done! Nothing complicated - things have certainly come a long way from just 2 years ago.
Now, in just an hour, the system was up, playing DVDs, with audio working. Good stuff.
So, will be sticking with Kubuntu for the next year or two at least. The basic setup has been completed very easily, and while the additional installs I need may not be that easy, given all that this system needs to do (web server, CGI scripts, some video editing/DVD creating, TeX/LaTeX), but who knows, it is probably much smoother today than it was just a year or two ago.
Some related links:
ubuntu-releases.cs.umn.edu has better description to the kits, better than the Ubuntu pages themselves.
lvm-configuration-in-ubuntu-810 lvm install tutorial using the alternate Ubuntu installer.
Get Kubuntu pages. The CD version is just fine, the DVD it seems, just contains extra language kits. So for US-English installs, the CD might be all that is needed. And go with the Alternate kit - far better install experience, with extra control available where needed.