if you try to run the game in software mode, it'll shut down after a very short while ...
add "cl_fxquality 0" into your "autoexec.cfg" and you should be able to run ESF (laggy)
I really recommend ... spend $10 into a video card ... goto eBay and buy a GeForce2 MX ...
ESF won't survive in Software mode ... but I think nowadays you have to be able to run OpenGL