I have been waiting to get into the world of Arduino: and I think I am about to make the jump.
I have bee specifically looking at the Arduino Duemilanove.
I have a signal that I am trying to count pulse widths as they go by. It is between 0V a 1V. I normally set the threshold for a pulse at about 0.2V, and I need to sample at at-least 10Ks/s (more the better though).
Has anyone used this hardware for a similar task?
Or is the computational power and sampling of the A/D out of ability?
At a rate of 10K samples per second you are pushing what you can get with the analogue input. It is much better if you can "square up" your signal using a simple transistor so that you can use a digital input instead of an analogue one.
Then you can use the pulseIn() function or interrupt edge counting.
Are you literally trying to measure the widths? Or just count the number of pulses, regardless of their width?
With a .2V threshold, you probably want to use some sort of voltage comparator (perhaps like the LM319, but make sure it can handle a voltage that close to the ground rail: I don't recall offhand), rather than trying to design your own circuit with discretes.
For best precision of measurement, look into using interrupts. But make sure that the interrupt you use has fairly high priority, so it doesn't wind up waiting for, e.g., a character-received interrupt to finish its calculations, which could skew your readings. A modified version of the code for pulseIn() might be just what you want.