Check ribbon cables properly seated betwixed CD and MOBO
Oh hang on, can't boot ? or install ?
Install: see above.
reboot with a start up floppy to safe mode and then find the config.sys file in the root of C: open it with notepad and delete its contents. Windows does not require this file since all the given devices are loaded by the registry anyway, so if there is a problem with it, empty it.
The only use for it is for old legacy apps to specify devices\drivers and for some programmers who leave something out of their 'killer app' and have to use this file(and Autoexec.bat)to modify system settings that are not registered.