I'm using a Kensington 72121 with a multi-boot system. It works fine with Windows
and Linux operating systems.

This Kensington model is no longer manufactured, but it's still available on a few sites.
The 72121 I'm using now is working ok. I prefer corded mice. Logitech's M500 seems
like a good substitute.

I've got some unique software running on 98SE that was created for my business. If I
keep 98SE the only way I could install Logitech's SetPoint software is with KernelEx.
I've tried KernelEx a few times. There were so many problems I always restored the
system before the KernelEx install.

Besides the big guys like Microsoft or Logitech I've noticed many other brands that I
don't know much about. Can someone suggest a mouse and software package that
is compatible with 98SE?

If you have  PS/2  port on the motherboard, that is the absolute easiest way to get around a driver issue like you're having.

 

It will work in every OS with no driver issues whatsoever. Plenty of optical PS/2 mice are available from a multitude of vendors.

I don't get it.

Is this the one? It says 98 and up. Also USB or PS2 "flavors".

http://www.bhphotovideo.com/c/product/414662-REG/Kensington_72121_Mouse_in_a_Box_Optical_Elite_Mouse.html

And this appears to be the attached photo in your post -

http://cheapwiredmouse.blogspot.com/2011/07/kensington-72121-mouse-in-box-optical.html

I've got some unique software running on 98SE that was created for my business.

So, what "features" are lacking that you need for this "software"? "Hotkeys"? (SMH)

 

BTW, why are you using Logitech software with a Kensington mouse?

Try using Kensington Mouseworks to see if it fits the bill.

http://www.majorgeeks.com/mg/sortname/specific_drivers.html

 

HTH