I'm not blaming the hardware motherboard itself as much as the drivers that go with it and win98SE's support for the board. The board and it's drivers are, however, the only significant "new" part of my system that are likely to be conflicting with my existing hardware.
It is very likely the microsoft provided SIS hardware drivers and having conflicts with UT and my SBLive soundcard and pherhaps the mouse drivers or DirectX8.1 or Detonator XP drivers. I was having 3 main problems in the end:
1. Both ps2 and USB mice locking up in UT
2. Sound from SBLive cutting in and out in UT
3. PC shut itself off at random once (and it was not likely a cooling or power issue, I checked)
There is no upgrade to UT beyond 4.36 , though I did look for known issues at several UT sites and BBS. I did not end up trying another D3D title, mostly because I determined that I could afford a KT266A board and DDR ram stick and I was running out of time where I could exchange the board. I tried all the mouse settings in UT that were available, and even checked my ut.ini and user.ini files for errors. SIS (and ECS) still use the default win98SE drivers that microsoft provides as drivers for the motherboard, and I checked for Microsoft updates. There were none that I could find, which left me to have to upgrade to win2000 or winXP to get more recent drivers, something I did not want to do, but which might have worked. So I had pretty much eliminated the option of upgrading motherboard drivers under win98SE. I also looked for mouse drivers and mouse bug fixes related to the problem I was having and found neither at both Logitech and MS websites. I also had thought about trying older Geforce drivers or going back to directx*, but decided that I was having to go through more trouble to get this board to run UT than the savings and down time I was having were worth to me. If i did upgrades or changes in the future, I did not want to worry about fixing all the same bugs and stuff. I don't want to pay good money to spend a week or two working out bugs..my hobby is gaming, not troubleshooting hardware and driver issues. The primary reason for this upgrade for me was to give my machine more life running UT and upcoming Unreal2 and such, and a PC that can't run UT is no good to me.
It is likely I could have gotten the mouse working in UT eventually, but not certain. I did, however, see 5 more opened K7S5A in a stack at the returns desk of the store I got it from, which makes me wonder if it was a lot of bad boards or something.
I ended up biting the bullet, admitted defeat (or lack of patience), and found a lovely EPox 8KHA+ for $99, and am now installing it in my system. Im not finished installing drivers and software, but will post followup tonight. I expect that this board, which has gotten excellent reviews, will work just fine.
As a side note, I have a UT Clan mate that has a system built with a K7S5A that works just fine, but we have fairly different hardware and he is using win2000 Pro.