There are plenty of Socket 370, Socket A, Slot 1, and Slot A boards that are packed with both pci and ISA slots that will run fine with cards like the AWE 32 or 64, Voodoo 2 cards, etc. My current DOS box is using a IWill KK266 with a Athlon 1ghz, Geforce card, and a AWE 32 infact. I don't have any issues with this set up. You do have to be mindful though that some of the VIA 133 chipset based motherboards had issues with Soundblaster 512 and Live cards in Windows though. Also, I wasnt just saying the 2k1 mark, I was saying up to it, because that is the timeline you pointed out for the Pentium 2 handling Windows related titles. As stated prior, the Pentium 2 started to show its limits for 3d games in 98. There are still a couple of years there in the time frame you mentioned that the PII was not up to snuff.
EDIT: So I don't look like I am talking out of my ass, for a example list:
Blood II: The Chosen, Carmageddon II: Carpocalypse Now, Carmageddon TDR 2000, Quake 3, DethKarz, Heretic II, Powerslide ,Star Wars: Rogue Squadron, Unreal Tournament, Daikatana, Shogo, Interstate '82, Requiem: Avenging Angel, Sports Car GT , NOLF, NFS High Stakes, Test Drive 6, Deus Ex, Rollcage Stage II, Heavy Metal: F.A.K.K.², Hitman: Codename 47, and MDK 2.
All of these titles were released during the 98-2000 time frame, and all of these titles get held back by the Pentium 2 when the games are running maxed out at 1024x768 or higher. No one wants to put up with sucky frame rates and low res/details. On titles like these a 550 mhz on up cpu is starting off good, and past that even better. Something in the 700-750 mhz range will give you a lot of umph, and 1 ghz is heaven (unless its a Celeron 1ghz, as those suck).