Speedometer/Tachometer combination

Hey there!
I want to build a Speedometer/Tachometer combination for my motorcycle with the help of an Arduino. It is supposed to have plenty of features, of which most seem to be no problem to implement. But I have one matter that I need help with. To calculate the velocity and show the rpm of the engine I need to measure two frequencies:
Wheel revolutions/sec, 1-30 Hz, ± 0,5 Hz(± 4 km/h), in theory I could add more magnets to double/quadruple the frequency.
Ignitions/sec, 10-200 Hz, ± 5 Hz(± 300 RPM).
Is there a way to determine both of these frequencies with one Arduino? I have found a few frequency counter libraries, but no one seems to be able to manage two at the same time.
Is this a case where an ARM Arduino would help due to multitasking?

Kind regards, Giulio

Those are extremely low frequencies... I think you could do it without getting that fancy - you're well within the capabilities of the chip. I mean really, you're measuring things 80,000+ times the clock speed of the chip. FFS, I measure the length of pulses of around half a millisecond, ie, ~2khz (albeit with nowhere near the accuracy you want) WITH DIGITALREAD, AND MICROS (ie, the worst way possible) in my RF receiving code, and it works like a charm at 8mhz.

What you're doing is surely within the capabilities of the chip.