It depends on what filesystem you are using with XP Pro. If you are using NTFS, then yeah, you will need to install 98 first. Otherwise, if you are running Fat32, you can probably install in any order.
I think you would be able to add an entry to the XP Pro's boot.ini that points to the windows install on the other drive (the D: drive) so when it's boot loader begins, it then begins reading from the the bootable image on the D: drive.
However, even if you have NTFS, I do believe the following procedure will work, but is a bit involved...
One final choice is to simply go to your BIOS and choose a different boot order. Many BIOS now let you choose your boot drive. So, you can simply say you want to boot from the D: drive. Yeah, it's a pain since you have to change each time, but ultimatly might be the easiest way to get this dual boot started.
First boot from XP and copy the 98 CD image to the D: drive that you format with a Fat32 file system.
Create or get a win98 boot floppy.
Take the floppy out and set your BIOS to boot from the D: drive. Before you make any changes, write down your boot settings, so you can return them if A) This doesn't work and/or B) we want to return control to the XP boot loader. Then, ensure the machine doesn't boot from the C:\ drive. It should fail to boot totally as long as the D: drive is not yet bootable.
Then boot from the floppy and begin the win98 install, making sure you install to the D: drive. Don't let it format or touch the C: drive. (I like this better than trying to build a boot floppy that contains CD drivers and such, and the install is much faster from an image already on the HD.)
You can then install windows to the D: drive, let it go through the reboots until it is done.
Then, go back to the BIOS and set it back to boot from the C: drive and your Windows XP should boot.
You have a file in C:\ called boot.ini
This file is probably system hidden and read only, so you might need to change some settings.
My two daughters each have a Win98 and Win2000 image on their hard drives. I did install Win98 first, and then Win2k, but you should be able to figure out how to modify the boot.ini to do this. However, make a backup copy of your boot.ini
Anyway MY boot.ini looks like this:
[boot loader]
timeout=5
default=multi(0)disk(0)rdisk(0)partition(2)\WINNT
[operating systems]
multi(0)disk(0)rdisk(0)partition(2)\WINNT="Microsoft Windows 2000 Professional" /fastdetect
C:\="Microsoft Windows 98"
In your case, you will probably have entries similar to the first two, after that you need to add something that looks like: D:\="MS Windows 98"
What my files means is the default O/S on the machine is on the second partition in the \WINNT directory. This is specified in the [boot loader] section
There is a second section called [operating systems] and this is where you can list all of the available O/S's and where they are.
It is in the [operating systems] section where you will list the location of Win98.
Now when the machine boots, you will get a menu to choose which O/S you want.
I believe the default timeout is 30 seconds, but I've changed my machines to 5 seconds. This is specified in the [boot loader] section.
I hope this helps, double check it, your mileage may vary. I'm not responsible if either I'm wrong or you screw up.
I wish you well.
TB
