VMWare gets my vote (except for 3D gaming). Got experience with all 3. VirtualPC had annoying bugs when I used it. Virtualbox doesn't fully cooperate with its virtual hardware when using 9x. Meaning there are things in Device Manager like the Advanced Power Management and a PCI System Peripheral that don't work properly. Plus it is slower than VMWare on 9x guests. No additions so must use SciTech Display Doctor Beta 7 and find the Keygen to keep it past the trial. The new version of Virtualbox has SB16 ISA available as a choice of audio and it works better than the Intel AC97 choice that needs the Windows 95 VXD Realtek AC97 driver (extract with WinRAR, point Device Manager to it) to work. My Creative SB16 Wave Effects software/driver cd improved the SB16 with their software, but the driver is nearly identical to the Windows 98SE SB16 driver.
98SE2ME works great on either VMWare or Virtualbox, but since VMWare handles the hardware better on 9x it is a truer real experience than Virtualbox is. Performance when using multimedia playback of things or software gaming is better on VMWare. Gotta say that SciTech Display Doctor was nice. Give you software OpenGL 3D when setting it to its CAD-most compatible choice. Only slow because Virtualbox is slow on 9x. I may try that someday using VMWare, installing the tools but updating the video driver to SciTech's. This all is after upgrading DirectX. That needs at least Direct X 7, but I install 9.0c anyway.
They offer a trial of VMWare Workstation. If you see it and like it (it really does 9x well) then you can buy it before the trial period ends. I found it just about the same speed as the real installed 98SE.
Edit -
And if you do check out VMWare Workstation, the audio is the ES1371 chip, the Creative/Ensoniq one that uses the drivers for the SB16 PCI. The SB PCI 128 WDM driver is what I end up with, but in the past I've installed the Creative Cd with the software and driver, then updated with the SB PCI 128 web update. It changes it from the cd's VXD driver to the WDM version properly. I used to need to edit the older VMWare version's Windows98.vmx file to get the audio to not speed up incorrectly but that's been fixed in the latest version.
I had a problem with the original VXD in the newer version of VMWare. It would cause a BSOD, and then the Automatic Skip Driver agent needed to be run and have it checked to allow again, but don't reboot. Just run the updater to the WDM and then reboot and you'd have the software and the WDM driver working fine. I'd manage to do this after recovering from the BSOD but even if not, you could still update it. If you don't have the cd then just installing the SB128 WDM by itself works and you'd avoid the BSOD of the VXD install. But no neat PlayCenter, Creative Mixer, Wave Studio, etc. Too bad since I thought the VXD driver was a bit better than the WDM updated one. Can't use it anymore.
You'll hardly notice you're not running 98 on a real computer with VMWare. Just a bit pricey though! Make sure to install VMWare Tools from the menu after 98's installed. Makes things better. If you do it before updating 98 with new Direct X, Windows Installer, IE 6 (not sure which causes it) I think you'll need to manually update the Standard PCI Graphics Adapter (VGA) to the VMWare Video driver in Device Manager. It shows up in the list after installing VMWare Tools.
VMWare Server is free, but I've never tried it. I think it turns off things by default that Workstation has on by default so it may need some tinkering. They have a Beta of the next version of Server that probably is better than the released version at this point. The released version of Server is really old.
Virtualbox kinda stinks running a 9x Guest so don't bother. For supported guests it's supposed to be great though, some say better than VMWare.
This post has been edited by Eck: 08 May 2008 - 02:10 PM