Why on earth are there people posting win-9x related questions here?
Doesn't everyone know that when it comes to win-9x (which I use full-time, as I'm using right now to type this reply, on a win-98se system with Kernel-Ex API enhancement and 2 gb ram) that they should either be posting to usenet (microsoft.public.win-98.gen_discussion) or to the win-9x forum on msfn.org.
http://www.msfn.org/board/forum/8-windows-9x-me/
All your win-9x questions have already been answered there. There's a specific thread for hardware.
I myself don't bother with win-95 (I have binders full of Micro$haft software, all versions of all OS's, from old MSDN cd's to technet dvd's). If you're going to run any version of 9x/me, don't bother with 95. 98se is what you want. There have been MANY MANY enhancements for it worked out by enthusiasts over the years that allow it to work with generic USB mass storage, large IDE and SATA drives, ram > 1 gb, etc.
When it comes to full driver support, the most advanced motherboard that you're going to be able to run win-98 on is something like an Asrock 4-core DUAL-VSTA or any other board with VIA KT800 chipset. The Asrock board has BOTH AGP and PCIe video card slots (only one can be used at any one time) and it has BOTH DDR and DDR2 memory sockets (again only 1 type of ram can be used at a time). I have 6 of those boards - 4 of which I have yet to use. All components of that board has win-98 drivers EXCEPT for HD-audio. There are no win-9x drivers for any HD-audio chips on any motherboard. So for sound, you disable on-board audio and use an old PCI soundblaster card. Basically, any motherboard that was new back in 2006, or any board that has AGP slot will have full win-9x (or win-98) driver support. Even if it has SATA-1 interface, there will be win-98 driver for the sata controller. That basically means you will be limited to Socket-478 Intel CPU's, unless the board has VIA chipset in which case the best you're going to do is socket-775.
If you have any more questions about running win-98 on "modern" hardware, post them on the win-98 group on usenet, or in the win-9x forum on msfn.