Perhaps because internal communication between those 1024 machines will be significantly more difficult than running on a machine that is optimized for parallel operations, RPC just doesn't cut it. You would probably lose a number of your hosts off the top just to coordinate the activity of the remaining machines. But DES-cracking and password-cracking are almost completely decomposable; no co-ordination is necessary after you've sent the ciphertext string and the starting point for the search. Besides, if you really want to do this spend your one or two million (approx cost of your 1000PC site) on seriously dedicated DES-cracking parallel hardware. Do the cracking in hardware, not software. Sure -- if you want a machine that does nothing but. Either way, I could think of more fun things to do with those 1024 PCs:) Well, there's been an interesting thread on rec.woodworking about hurling strange things with medieval siege engines...