Install Windows 98 first. Upon installation, Windows XP will prepare a boot menu with two entries: one for 98 and one for itself.

I use this way (NTLDR + Win98's bootsect), each OS thinks it's installed on drive C:.

Indeed it's easier to first install Win9x, then XP. Because XP recognizes Win9x automatically, but not the other way around. Win98 will probably trash the XP boot sector.
If you don't want to wipe the existing install, there are ways to fix / work around it. I've documented some of them here.
ott's suggestion has its own advantages, I would try that first, if you already have WinXP installed.

I did just that not long ago on a laptop.
I used this tool to reduce the size of the XP partition after defragmenting it. It was freely downloadable from https://web.archive.org/web/20160310034551/ht … m/download.html

And it's mirrored at https://archive.org/details/minitool_partitio … ee_edition_v9.1

Installed Win98se, then you have the choice of installing BeOS Personal Edition under Win98 (if your hardware is supported) and install bootman (the BeOS bootmenu) from the Terminal.
Or boot from a Haiku livecd and install its bootmenu.
It will show one entry per partition and will works flawlessly.

If I wanted to install Win98SE first, how would I format the existing WinXP installation?

I used to be able to do this stuff but it’s been so many years…

The Windows XP partition can be formatted from a Windows 98 boot disk. Navigate to the installation medium and run "extract ebd.cab format.com"; this will make the format command accessible. Formatting the partition from a later Windows installation medium is also an option.

GemCookie wrote on 2025-07-13, 15:13:

Formatting the partition from a later Windows installation medium is also an option.

Would you say it’s easier from WinXP’s disk?

AndreaColombo86 wrote on 2025-07-13, 17:54:

Would you say it’s easier from WinXP’s disk?

The Windows XP installer is more likely to allow a quick format.

First things first what are the system specs? Are you sure the hardware supports Win98?

Second WinXP still has EAX support (It's the last OS that does) so if thats your main reason for the downgrade then no need!

If you want to install both just for nostalgia then that's perfectly valid reason.
Personally I work on the theory prepare the system with the earliest OS and your guaranteed full compatibility.

So in this case, I'd use Fdisk to partition the drive. Typically I go with
4GB Fat32 Primary partition for Win98 (C:\)
Extended Partition
Large Fat32 Logical partition for games and data (D:\)
10GB NTFS Logical partition for WinXP (E:\)

This will mean your drive letters remain the same no matter which OS you boot into (E: will just disappear when in Win98)
It also means if you need to reinstall all your data is safe in its own drive.

I would finally say it may be worth getting a second hard drive to test with. leaving your currant hard drive safe in case everything screws up

Thank you, chinny22.

I’m currently considering two different retro machines. One has a P4 2000mhz, 512Mb RAM, a GeForce 4 MX460 and an Audigy 2 ZS sound card. From what I could gather online, all hardware here has drivers for Windows 98.

The second machine is a P4 3000mhz, 1Gb RAM, a Radeon X550XT, and no sound card (I would buy one separately). I believe this should also work with Windows 98.

The EAX thing is a bit particular, as it has to do with specifically with the occlusion effect in Baldur’s Gate 2. It turns out it doesn’t work on Audigy sound cards with WDM drivers, so if I run one of those, I need VxD drivers to get occlusion—hence the need for Windows 98.

From what I read in another thread here on VOGONS, older Creative sound cards like the SB Live! still provide the occlusion effect with WDM drivers, so I’m now deciding whether to go with an older card and keep Windows XP, or get a newer one and dual-boot Windows 98.

AndreaColombo86 wrote on 2025-07-14, 10:57:

Thank you, chinny22. […]
Show full quote

Thank you, chinny22.

I’m currently considering two different retro machines. One has a P4 2000mhz, 512Mb RAM, a GeForce 4 MX460 and an Audigy 2 ZS sound card. From what I could gather online, all hardware here has drivers for Windows 98.

The second machine is a P4 3000mhz, 1Gb RAM, a Radeon X550XT, and no sound card (I would buy one separately). I believe this should also work with Windows 98.

The EAX thing is a bit particular, as it has to do with specifically with the occlusion effect in Baldur’s Gate 2. It turns out it doesn’t work on Audigy sound cards with WDM drivers, so if I run one of those, I need VxD drivers to get occlusion—hence the need for Windows 98.

From what I read in another thread here on VOGONS, older Creative sound cards like the SB Live! still provide the occlusion effect with WDM drivers, so I’m now deciding whether to go with an older card and keep Windows XP, or get a newer one and dual-boot Windows 98.

For the Win98 side of things CPU doesn't really matter. Win98 can't take advantage of Hyper Threading, but this doesn't really matter as the CPU itself is still crazy fast for WIn98 and it'll just "ignore" the HT.
For WinXP the faster the CPU the better. It's a cheap easy upgrade.

More Important is what chipset the motherboard uses, most P4 era do support Win98 but some are better then others with Intel 8x5 being a safe bet. eg 845, 865

GF4 MX is a very compatible card for Win98 side of things but underpowered for WinXP (but then so is any card with Win98 support)
The Radeon is more powerful which will benefit XP but drivers aren't as stable.

Audigy 1 and 2 still support VxD drivers, Although Audigy 2 by default installs WDM. Joseph Joestar did a very good guide on how to do a clean install of VxD
Guide: Installing Windows 9x and DOS drivers on Audigy cards (version 3.1)

I'm not familiar with the Baldur’s Gate issue so not sure if it just requires VxD or specifically a SBLive!
I'll admit I don't really notice any difference in sound quality between a Live and Audigy 2.
The main benefit is the Audigy will give you EAX 4 support if any of your games use it.
https://www.vogonswiki.com/index.php/List_of_ … ith_EAX_support

Thanks again.

The P4 3000Mhz, which is the machine I’m keen on, has a Gigabyte 8TRC410MNF-RH motherboard. From what I could gather, it’s an ATi chipset. Do you reckon that could work with Win98?

For now I’m leaning toward getting a SB Live! 5.1 card and running WinXP. I can always get an Audigy at a later date and dual-boot Win98 if needed.

If you want to use DOS programs in Win98 mode, on my Win98SE system, I was only able to get UMBs and EMS using UMBPCI. If you can't get UMBs or EMS on your system, try that. 😀

AndreaColombo86 wrote on Yesterday, 21:13:

Thanks again.

The P4 3000Mhz, which is the machine I’m keen on, has a Gigabyte 8TRC410MNF-RH motherboard. From what I could gather, it’s an ATi chipset. Do you reckon that could work with Win98?

For now I’m leaning toward getting a SB Live! 5.1 card and running WinXP. I can always get an Audigy at a later date and dual-boot Win98 if needed.

im not sure how compatible ATi chipsets are with win98, i dont really hear people talk about them when it comes to 98 or just in general, if your going pentium 4 (which is a good choice for 98/xp) i'd play it safe and stick with either an Intel, VIA or SiS chipset.

Not familiar with that chipset either but it's not looking good for Win98 compatibility after a quick search.
https://theretroweb.com/motherboards/s/gigaby … -1-1-oem#driver

It has native IDE so you'll still probably be able to install Win98 but it won't recognise on-board components like USB, SATA, Audio.