When I read your thread, I immediately thought that it would be too easy to break. Certainly not for an ordinary person, but still: "Computer programs used for brute force attacks can check anywhere from 10,000 to 1 billion passwords per second.", but i did some calculations and:
number of combinations - 24! (24 x 23 x 22 x 21 x ... x 3 x 2 x 1)
24! = 620,448,401,733,239,439,360,000
Assuming 1 billion tests per second, the correct order will be 100% cracked in 19,631,267,468,771,206 years! half of this time to be 50% sure. I think its secured enough! At least to my knowledge