First, the good news. I now have my Fujitsu Lifebook S6510 set up to quad-boot XP/Ubuntu/openSuSE/Mandriva! That's certainly worth a few giggles. More importantly, it will make it a lot easier for me to track and compare the various Linux versions, on the same platform. It actually all went very smoothly; details below.
Second the correction. In an earlier post I said that the openSuSE installation did not recognize a previously installed Ubuntu partition and set it up to dual-boot. I was completely wrong; the problem wasn't in the boot setup, it was earlier than that. When I went through the disk partitioning in openSuSE, it came up with its own idea about how and where to install, and then gave me three options - accept, edit partition map, create partition map. I chose edit, and didn't realize that what it gave me to edit already incorporated the "suggested" layout it had come up with - nor did I notice that it had taken over the partition in which Ubuntu was installed, to be used as /home for openSuSE. Chalk that one up to a combination of inattention and inexperience. So, by the time the boot setup procedure came around, the Ubuntu partition was already history. This time, when I set up the quad-boot configuration, I chose "create" instead of "edit", and it gave me the original map as a starting point. I put openSuSE in its own partition, and the boot procedure recognized and configured the Ubuntu (and XP) partitions correctly.
Third, the details. The specific procedure and partitioning that I chose for this quad-boot setup are based on trying to keep the installations as simple as possible, and maximizing the multi-boot flexibility both now and in the future if I decide to add more to this. Therefore, what I did was install XP Professional in the first partition on the disk (I basically have to do that, because I am restoring from Fujitsu "Recovery" DVD, not installing from true Windows distribution media), then connect that disk to another system that is already running Ubuntu, and use the partition editor to create a FAT32 partition where I will keep my documents, pictures, videos and such, and an "Extended" partition which covers the rest of the free disk space. I then created multiple partitions within that extended partitions for Linux. It is interesting to note that all of the versions of Linux that I have tried so far (and I suspect all versions, period), use the same kind of swap space, so I was able to create only one swap partition, and they all use that. Then it was just a matter of installing the Linux versions one by one, and being very careful about disk allocation each time. As each one was installed, it recognized those previously installed, and added them to the "new" boot menu. Very nice.
More to come...