For 256 to 384Mb I multiply it all by 0.50
For over 384, I keep it at 384 x .25 x 1024 x .5 = 49152...
(which is getting pretty stinkin huge, no sense going any
larger no matter how much ram you have)
For the Min amount, just halve whatever the Max amount is.
Chunksize is always 512. (In fact, that's the default)
128 megs x 0.25 x 1024 = 32768 max
128 megs x 0.25 x 1024 x 0.75 = 24576 max
256 megs x 0.25 x 1024 x 0.75 = 49152 max
256 megs x 0.25 x 1024 x 0.50 = 32768 max
384 megs x 0.25 x 1024 x 0.50 = 49152 max
sprint