Are you sure you really want to do this? According to my calculations, (assuming I didn't make a mistake) that is at minimum 62^16 possible passwords, just counting letters (both cases) and numbers. This comes out to 4.767240e+28 possibilities. Assuming you can check 1,000,000,000 passes per second, it would take you 1.510647e+12 years to check all of them.

What most password cracking programs do is use a dictionary of words and/or phrases, and make variations on those (ie. convert letters to numbers, i -> 1, o -> 0, etc.) and check all of those. Brute forcing large passwords is very time consuming.

There are a number of good password cracking programs out there already to check your systems, such as John the Ripper.