@SquallStrife
It worked! Your help was most appreciated. It saved me quite a bit of searching and reading. I can now boot to Win98, NT4, and W2K using the default W2K bootloader and the partition sizes I wanted. I used dd-0.5.zip, and for my configuration, the dd command used was:

dd if=\\?\Device\Harddisk0\Partition3 of=bootsect.w98 bs=512 count=1

Then added,
c:\bootsect.w98="Windows 98"
to the boot.ini file on the W2K partition.

There is only one thing left to do, get XP Pro installed. I have 12000 MB for this final partition. The options are to install WinXP:

1. After Win98SE as FAT32
2. After Win98SE as NTFS
3. After W2K, but before Win98SE, as FAT32
4. After W2K, but before Win98SE, as NTFS

I'm going to opt for option 4. first. I recall how W2K didn't like being behind the 8 GB barrier, but I'm hoping XP has a workaround for this. If it fails, I'll try option 3, then 1.

Will I need to recreate the bootsect.w98 file after the Win98 partition becomes \Partition4 ?

EDIT: I've noticed a lot of problems come along during this process of moving partitions and installing a new OS. As I am installing XP right now with option 4, XP setup thinks the XP partition is #4, so it sets the boot.ini according to this. But after the first phase of installation and a reboot occurs, Windows can no longer boot intself because the partition is really partition #3. So you need to use the Partition Magic Rescue discs to set the WINNT partition as active, boot into NT4, then change the boot.ini on XP partition to reflect that it is partition #3. I had to do something similiar with the W2K installation as well, but the changing of the partitions came at some point later when I unhid all the other partitions. Again, boot into NT4 to correct the partition number on the boot.ini for the W2K partition.

All 4 OS's now boot from the single XP boot loader. This is the disk configuration,

NT4, 4 GB, NTFS (installed second; must start as FAT and convert to NTFS later)
W2K, 8 GB, NTFS (installed third)
WinXP, 12 GB, NTFS (installed last)
Win98SE, 8 GB, FAT32 (installed first, then shifted right into unallocated space to make room for W2K, then XP)

I even added the WinXP Recovery Console into the boot loader.

This setup took a lot of little tinkering. I needed to reassign drive letters in WinNT using the Disk Administrator. Each time a new OS was installed, W2K, then XP, WinNT would loose drive C: as its own. WinNT would be come D, but you can swap this with Disk Adminstrator and reboot.

As WinNT sees things,
C: WINNT
D: W2K
E: XP
F: Win98 (FAT32 for NT4 is installed, so I can view/read/write to FAT32 discs)
Z: DVD-ROM

As W2K sees things,
C: W2K
D: WINNT
E: XP
F: Win98
Z: DVD-ROM

As WinXP sees things,
C: XP
D: WINNT
E: W2K
F: Win98
Z: DVD-ROM

As Win98SE sees things,
C: Win98
D: DVD-ROM

Case closed. I hope it clones well onto other hardware. I figure, boot into safe bode, remember everything from device manager, and let it get redetected. This worked well for me for Win98SE during the Ultimate 686 Benchmark Comparison. Hopefully the other OS's behave now.

I have come to the point in this system where I am installing Windows updates. It looks like Microsoft no longer allows for Windows Updates for W2K, which is a relatively recent development. Within the past 16 months, internet Windows Updates for W98SE, W2K, and NT4 stopped working. They used to at least allow you to install the old updates. I patched the XP partition with Windows Update.

Microsoft still has the W2K and NT4 updates on their website. There are about 30 patches for NT4 and over 200 for W2K. For whatever reason, there are only 2 for Win98SE, so I applied those two first, then the unofficial service pack.

The question is, NT4 and W2K want to reboot after every hotfix, but there is no way I am going to reboot 200 times. Is it OK to install them one after the other without rebooting? Will Windows get patched correctly?

I figured if any of the hotfixes are patching the same file, it would be best to patch them in order from the oldest patches applied first, then go up by date (newer). This is how I did it anyway. I saved all hotfixes with their date first and double-clicked away. I first installed all service packs and only downloaded hotfixes after the date of the most recent service pack roll-up. What is the most appropriate means for patching Win98SE, NT4, and W2K?

as far as 2000 & nt4 goes, I'd install the last service pack and thats it. I don't think there is any point in wasting your time past that.

W2K and NT4 each had about 5 yrs worth of patches after the latest service pack. I suppose I would have to go through what they patched to see if they are of any value. Does anyone know the proper patching methodology outside of online Windows Update? I already installed all NT4 and W2K post-SP patches; the OS works as expected at least.

As I understand it, the vast majority of small security patches end up bundled as "rollups" also if these machines purpose is only benchmarking then I dont see the benefit of patching security holes.