Yes you an do 1kHz very easily.

As with all frequency measurements you have two choices...

1. Meausre the Length of a Pulse

Here you measure the lenth (in time) of the input signal... so for example you can use PulseIn, measure the Positive Going part of your cycle, then measure the Negative going part and add the two together. Another way would be to start a timer at the beginning of your first cycle, then stop the timer at the start of the next cycle. The timer will then tell you the length of the cycle.

2. Measure the number of Pulses in a Set Time

Using either an internal or external timer, you simply count the number of pulses received in one set time period. Here you can also use the Capture Compare feature of the CCP Module if your PIC has one (the PIC's Datasheet has all the setup details).

I posted an Olympic Timer last week in the Code Examples section... it should take all of about ten minutes to trash that code and convert it to a simple direct-reading Frequency Counter as a starting point.

Melanie