Hi,
Speaking from experience, this process is quite... painful.
The others were correct in saying the simplest way is to repartition and format your drive. Windows 98 attempts to install onto partition 1. IIRC, if it detects another file-system it gives you only two choices: to format the partition (losing all existing data), or to cancel and stop the install.
This leaves you with a number of methods:
#1 - Redo everything, install 98 on partition 1, and XP wherever else (2).
This method is the easiest and the safest. Simply back up all important data. Re-manage your partition layout so you have an unallocated space for 98. Install 98, which will now be C:. Put in the XP disk, reboot, and format and reinstall Windows to your XP partition (2). XP will now be D:. The boot-loader prompt will be set up by default for both OSes.
#2 - Use VMware
Only applicable if you have access to it (e.g.: work). Makes multi-booting incredibly simple.
(Note: Anything past this point is pure speculatory. I haven't tried it.)
#3 - Convert XP partition to FAT. Install 98 on same partition as XP
Title pretty much says it all. Make sure to install to a different directory than \WINDOWS. After, follow the steps outlined in #4 to be able to boot XP. However, I wouldn't recommend this due to the undisputed superiority of NTFS.
#4 - Move XP partition forward, install 98 on the now-free space
This is risky. Basically, what you want to do is move the XP partition forwards to leave unallocated space behind for 98 to install to. This can be achieved with tools such as Partition Magic. Afterwards, format this space to FAT. Then follow these steps (note that this is before you install 98):
- Copy ntldr and NTDETECT.COM to the root directory of the 98 partition.
- Copy boot.ini to boot.ini.xp on 98
- Install 98
- Boot into 98. Replace 98's boot.ini with boot.ini.xp. Increment the partition number[s] inside by 1 (e.g.: if XP was partition(1) change it to partition(2)). Then, insert C:\="Microsoft Windows 98 [SE]" at the bottom of the file.
- This part is essential. Since you're setting up the dual-boot manually, the bootsect.dos file is not created. Read more on creating it here.
- The boot sector now needs to be replaced for XP. Put in your XP disk and reboot into repair mode. Run 'diskpart' to find the drive letter for the 98 partition ('map' might show it too, I forgot). Then run 'fixboot C:', where C: is the letter for the 98 partition.
If I didn't omit anything, that should do it. Quite complicated, if you ask me.
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As you may note, simply backing up the entire XP partition, installing 98, and restoring XP to a new partition won't work. The 98 partition would take precedence and the drive letters would change, leaving XP unable to boot. (There are some automatic drive mapping programs out there but in my experience they suck)
Good luck
