Okay, I don't know who the techno Henning is, but I know that I myself am a pretty cool kind of Henning
First of all, I have found that 120-133MHz is perfect for pretty much all games, anything beyond that would trigger timer problems in Space Quest and the like. I had a PC with 75MHz which was a tad too slow. 90MHz might just be enough, but I prefer being on the safe side.
As for RAM, I always figured 32MB to be perfect until I found out that some games have problems with more than 24MB. 24MB was also the amount that was considered ideal in my previous PC-building threads (ages ago). Maybe we could incorporate game reports regarding performance/setup etc. in this document of mine
I agree that ISA is an absolute must for any DOS machine. I have tried the basic SB16 on various occasions and found it to be adequate. However, I have also used a Compaq ES1868 in the past, and from my experience, this particular model is simply the best among SB16-compatibles. But, I'm open for suggestions!