Maybe I'm not understanding what your experiencing,cause if you can't boot into safe mode and you can't get windows to boot.Since after you installed the drivers
your system would hang and prevent you from booting into safe mode,so it's probably the divers for your AGP card causing the problem. This is why I recommended a starup repair so you could get your system up and running. Windows would install a standard vga driver
for your card. Then once you can get into device manager we can figure out how to install a working driver for your specific card. So if your thinking the video card drivers are causing the problem why would you want to install them first? Wouldn't you expect the same out come?