Sure, ^-^
the redirect is pretty simple, and im sure you know what that part does,
redirects the registry to its own file,
now, the 'keep in memory' bit actually does two things,
first,
it speeds up the program, its quicker to access things in memory then on the drive,
you can test it with it off, and if you dont notice that much of a slow down, then it most likely wont matter,
but sometimes that slowdown, like when the program starts can be 10-30 seconds if not more,
(used to be alot longer back in the beta days *shudder*)
and secondly, as you seemed to have guessed, it prevents the program from constantly writing the memory stick, so it last longer,
Though, even on a machine with 512 Ram, you should be ok,
my biggest .reg file is only 100-150k, which is pretty much nothing unless your running alot of high memory programs and need every bit you can get, (in which case id recomend going and getting another 512 stick,

)