http://www.diehard-software.org/ DHard eliminates — or greatly reduces the likelihood of — a class of bugs and security vulnerabilities called memory errors. DHard actually prevents certain kinds of errors from happening at all. It also reduces the probability that a bug will have any effect at all. DHard works by randomly locating program objects far apart from each other in memory. This scattering of memory objects all over memory not only makes some errors unlikely to happen, it also makes it virtually impossible for a hacker to know where vulnerable parts of the program's data are. This thwarts a wide class of exploits. Its about as simple as you can get...on or off
To me...if firefox is all it affects(80mb ram is that high for ff?), and it adds stability AND security then its worth it. It looks worth a test run anyways...