Windows XP 32-bit SP3
nVidia 660 GTX

The flickering is so bad that I can barely see Tex's bed let alone the Pachisi game that is suppose to be on it.

try changing the driver

Configuration only gives me display/Primary Display Driver.

no your display driver, It may not be compatible with the game. I remember one time I updated my gtx 460 & I got corrupted video in overseer so I had to go to the previous driver. what version driver are you using. the latest is 331.82.
Overseer does not like dual cards either & play under one cpu .

Let's see, the GeForce 600 series cards were first released in 2012.
Overseer was released in 1998.
Unless you know of a specific version that works this line of thought isn't that helpful. Any suggestions on how to address that?

you haven't told me what driver you are using, did a test on win 764 tonight & my driver 331.65 causes bad corruption
so I am unable to select save game , so I changed to on board graphics & no problems there.

its certainly the driver so try a previous driver.

What driver I'm using is irrelevant since it has flickering. The question was what version do you suggest that doesn't. Do you know or not?

Also what do you suggest for addressing the dual card or CPU problems you mentioned?

since you are using xp you can install image.cfg but it doesn't work on 64bit so you could use .
http://www.sevenforums.com/tutorials/83864-processor-affinity-add-set-affinity-context-menu.html
install this & everytime you start overseer right click & select run with 1 cpu.

this will only help during game play with crashes & not screen flickering. you have use another driver for that. all drivers work for overseer except the one you are using.