I should note, I wrote an article on this awhile back. Take it with a grain of salt, as I'm not an expert in the area; I just wrote bindings for the ISAAC algorithm to Perl.
http://jawnsy.wordpress.com/2009/06/04/performance-of-mathrandomisaac/ It compares the performance of multiple different PRNG modules (code for this is in the Math::Random::ISAAC examples/ directory). I've included charts of the distributions generated by them and benchmarks of course.
