After wasting way too much time finding and testing this, I'm convinced that there's no way of running this with a GeForce video card, regardless of the OS.
The only way I was able to even to get some response was to try it on my 566-Celeron2 rig which has a Lightspeed128 video card (using the TSENG ET4000 chipset, which UniVBE likes) and an AWE64 ISA soundcard for maximum "old-game" compatibility. Even then it had major issues.
No surprise that UniVBE isn't needed, as I got the same results with or without it. Using Win98 at the DOS-level, it repeatedly locked up on the 1st frame of video. If I forgot load a mouse driver it would display the main menu...then lock. This was with or without sound.
The funny part was that it was the soundcard causing the problem...even though it wasn't being used. The patch called newangel.zip fixes the soundcard issue (even got SB16/AWE sound), but from the ReadMe:
IMPORTANT: This patch will cause a lock at the beginning of the second disk. To address this problem, a saved game is included in this archive. This game will start you just after the lock point. When you Unzip this patch into the ANGEL directory on the hard dirve, the files for the saved game named "workaround" will also be copied, and you will see this in the first saved game slot. DO NOT SAVE OVER THIS GAME. When you reach the point in the program at which the lock occurs (shortly into the second disk, after you disarm the grenade), load the "workaround" game and continue from there.
This update fixes a problem using the Creative Labs PnP (Plug and Play) sound card and it also contains an earlier patch which fixes a problem accessing disk #2 with older Sony CD-ROM drives like the CDU 33A.
So they traded one problem for another...
In any case, I believe that the video card is the key...