I found Windows 98SE stable on a few of my machines either in the past or present using the following configuration per system:
Past setup:
Socket 3 system:
PCChips M912 v1.7 (genuine L2 cache installed), later a Shuttle Hot 443 motherboard (integrated I/O)
AMD Am486 DX4-120, later an AMD AM5x86-P75
24MB SIMM-72
80GB HDD (overkill, I know, but, that was the only HDD I had), 7.8GB partition (for a 486 motherboard, that's surprising that it accepted the HDD in the first place)
Lite-On DVD Burner
AT style keyboard, later a PS/2 keyboard that plugs into a PS/2 to 5-pin DIN adapter
S3 Bahamas Paradise 64 2MB VLB video card, later the nVidia GeForce4 MX4000 PCI video card
Sound Blaster 16 CT4170, later an ESS Maestro-2 ES1968S (Diamond Sonic Impact S70)
WinBond Multi I/O controller (1x IDE, 1x FDD, 2x RS-232, 1x LPT, 1x GamePort)
El Cheapo 3.5" floppy drive (installed mid 2012)
Overall performance was good, but, Windows 98SE took a lot of resources
Socket 7 system:
Past
DFI P5BV3+ Rev. B+ (VIA MVP3)
Enlight AT PSU (230W), upgraded to an ATX PSU
AMD K6/2-300
96MB SD-RAM (put 576MB SD-RAM in for Windows XP)
ESS Maestro-2 ES1968S (Diamond Sonic Impact S70)
3Com EtherLink III 3C509-Combo
RealTek RTL8029(AS) PCI Ethernet
SiS Mirage 305 PCI video card, then nVidia GeForce4 MX4000
3.2GB-6.4GB Western Digital Caviar HDD (both stopped working years ago)
48x Lite-On CD-ROM
3.5" FDD
This setup had stellar performance
Present
520W Corsair ATX PSU, with the ATX-ATX w/ -5VDC adapter installed
Abit AB-TX5 motherboard (Intel i430TX chipset)
AMD K6/2-300
128MB SD-RAM
3.5"-5.25" HDD bay for easy insertion and removal of a hard drive
200GB HDD (32GB limit set due to the BIOS limitations)
Lite-On CD burner
LS-120 SuperDrive
3dfx VooDoo3 3000 PCI (installed a fan on the heatsink)
Sound Blaster 16 CT4170
D-Link FastEthernet PCI
SIIG I/O card (2x RS-232, 1x Parallel, 1x GamePort that's disabled)
Performance is pretty good, but, the lack of an AGP slot begs to differ
HP Pavilion N3350
AMD K6/2+ 550M
64MB SD-RAM
HL-DT-ST DVD Burner
Trident video (could be wrong)
4.6GB Fujitsu HDD
3.5" FDD
Not bad performance, wish the video card wouldn't stretch the display at 640x480 at all, especially in DOS.
Shared HDD, Optical Drives, floppy drive, case, and other resources (video, sound, and so on) system
Items used:
400W ATX PSU w/ an ATX-ATX w/ -5VDC adapter since there's an ISA slot on there
Maxtor 60GB HDD (NIB at a thrift store)
HL-DT-ST CD Burner
Samsung DVD-ROM (currently not reading discs again)
Creative Labs Sound Blaster Live! 5.1 Platinum (IR Drive installed)*
3.5" FDD
nVidia GeForce 6200 PCI video card
STB BlackMagic VooDoo2 card (not installed at the moment due to 2 broken off capacitors that I will install later on).
Ultra ATX case
Socket 370 (benchmark board)
Shuttle AV18V31 (AV18E2) (VIA Apollo Pro 133T)
256MB SD-RAM (only 1 SD-RAM slot works of the 3)
VIA C3 700A (was installed previously), currently Intel Celeron 1.4GHz Tualatin
Universal AGP slot (1x, 2x, or 4x supported)
RealTek RTL8139D FastEthernet PCI
Overall performance is pretty good, but, some games do shutter a little bit
Socket 462(A)
DFI KM266Pro-MLV
AMD Sempron 2200+ 1.5GHz (will replace with a 2.167GHz Athlon XP 3000+ or 2.05GHz XP 2800+)
256MB DDR-333 (actuallt 240MB since I have a PCI video card installed currently)
VIA KM266 chipset
VIA FastEthernet
S3/VIA integrated video (disables when an AGP card is installed)
VIA AC'97 Audio (disabled since I have the Live! 5.1 installed)
Overall performance is better than the K6/2-300 system, yet, I should install an AGP video card to get all 256MB RAM
IBM ThinkPad R40*
Intel Pentium 4-M 2.0GHz
256MB DDR-266 (has 1GB DDR-266 now for XP Pro SP3)
20GB Hitachi HDD (starting to go bad, will clone to a new HDD in the future)
ATI Radeon Mobile 7500 16MB
Overall performance was pretty good, but, some games require a better video card and higher video RAM
Socket 754**
PCChips M871G motherboard (SiS chipsets)
AMD Athlon 64 3000+
256MB DDR-400 (now has, I'd say 768MB RAM installed)
SiS Mirage 2 integrated (disables with an AGP card in the slot)
RealTek FastEthernet (cannot remember the chipset at the moment)
Overall performance was pretty great and games ran better than I imagined
* currently has XP Pro SP3 installed and running without issues, except the HDD is starting to go bad and I'm going to replace the HDD with an SSD option (mSATA to 44-pin IDE) and gotten repaired after I accidentally ripped the power fan connector of the board when replacing the thermal compound.
** the board is back in the case that runs Windows XP Pro SP3