should be...do you have a software program to overclock or are you planning to use the bios... if you use the bios to overclock, try bumping up your FSB a notch or two at a time, leave your multiplier as is and see how it reboots...
On my K7N2 Delta L nForce II 400 edition MSI board, I run a athlon xp 2500 (1826 mghz)
using my bios I took my FSB,from stock 166 to 200 left multiplier alone which it now is 200 FSBX11multiplier= 2200 mghz or athlon xp 3200 without changing anything else. I left voltage alone etc.
Don't know if this helps, you might have a different setup, not sure of 2100 athlons
good luck