Anyway thanks for the code examples, I'm pretty sure I can learn something from them.
Yes you get 500 times the attempts in the 30hr period. But if you run the figures it's something like 0.00000001% difference in the amount of keyspace you can cover :)
AKA just run it on a couple of PC's an hope you get lucky!
Had very similar thinking, but decided against it because of usage policies. :-p
Be careful. This is not "exactly" legal, and it could hurt you. Make sure you also throw some legitimate computational work at the clusters so you have an alibi at least.