BPM: Divide BPM by 60 to get beats per second. A "beat" is equal to a quarter note. Multiply by two for 8ths, and 4 for sixteenths. That gets 13.333 notes per second for 16ths at 200 BPM. That's pretty fast ;)

Alternate Solution: hook up your guitar to your comp via line in and a 1/4 in. -> 1/8 in. converter, or plug a mic in your comp and mic your amp. Using Sound Recorder, or some other recording program, record a set pattern to which you know the # of notes (like Am scale pattern from 5th fret low E string to 10th fret B string, 15 notes). Record yourself playing these 15 notes, or some other pattern, then divide the notes you played by the seconds it took you to play them, and you have BPS.