It's running correctly. AMD ranks their CPUs differently then Intel. Since AMD's are more efficient, an AMD 2100+ (running at 1.73 ghz) is "roughly" equivalent to a 2.2ghz Pentium IV.

I have an AMD 2500+ running at 1.83 ghz.

Edit -- actually, it's overclocked to 2.2 ghz (AMD 3200+), but you get the idea.