It's all trial & error. Your PC2100 is gonna hold you back, plus your board is nothing to right home about either. Ideally, you'd want your CPU unlocked so that you can lower the multiplier, & crank up the FSB.
For example...your CPU is normally clocked at 13 x 133MHz (1733MHz), if it was unlocked AND you had a decent board that supported 200MHz (400FSB), AND you had PC3200 RAM, you would be able to run it at 9 x 200MHz (1800MHz). The overall CPU speed gain isn't significant (67MHz), but the change in FSB speed from 133MHz to 200MHz is DEFINITELY significant!
With that board & that RAM, you'd be lucky to hit 150MHz FSB IF the BIOS allows you to raise it that high. 140-145MHz is probably more realistic. You may need to increase the CPU voltage, RAM voltage, or both. Loosening up the RAM timings will allow it to run at a higher bus speed too.
Asus A7N8X-X Athlon XP 1800+ @ 8 x 210MHz 768MB PC3200 @ 210 MHz Asus Ti4800SE 128MB WinME/WinXP Pro SP1 Super-Flower 350W PSU
Soyo SY-KT600 Dragon Plus v2.0 2500+ Sempron @ 10.5 x 185MHz 512MB PC2700 @ 185 MHz GF4 MX440 64MB WinXP Pro SP2 Super-Flower 350W PSU