There must be a typo with your Service Tag number.  It comes back to an older Optiplex system.  Otherwise... when you installed Windows 2000 did you also install the chipset driver?  The chipset driver must be one of the first drivers installed in order for the hardware to be detected correctly and for the other drivers to install properly.  You can click here for the chipset driver used on the 4300 with a Windows 2000 operating system.