You can use <b>Jumperless Mode</b> to find out, but if I remember correctly, it should be 1.625/1.650V for core voltage.
VID1 (1-2)
VID2 (1-2)
VID3 (2-3)
VID4 (1-2)
For I/O Voltage (VIO), it should be at <b>Default</b> 3.45V (2-3).
Actually, Duron's setting almost is same as Athlon's except some fields in <b>Advanced Chipset Setup</b> of <b>BIOS</b> such as <font color=blue>PCI Master Read Caching</font color=blue>, Asus recommends <b>disable</b> to Duron.
Your Duron 800MHz should be run at 100MHz FSB with Multiplier of 8 (100X8) or if you run at 133MHz FSB you could lower your multiplier (X6).
Good or Bad have no meaning at all, depends on what your point of view is.