Patio, yew are the one that said "768MG" and did not explain for us laymen what MG means. Was this a reference to your daily Valium dose?
it obviously means MeGabytes...
First off, it could not mean dosage for anything, since the metric prefix for "milli" is a lower-case m, and the prefix for gram is also lowercase; whereas both letters are capitalized here. Additionally, the meaning can be derived from context quite easily:
with 128 MG of RAM
As you can see here, 128 MG is being used to measure RAM. therefore, one can logically conclude that it measures Memory size, and therefore, Even though MG is not an accepted prefix the only thing that it could indicate is Megabytes. This conclusion is further supported by the fact that the numbers agree with general recommendations regarding memory and Windows XP. Any conclusion to the contrary is one based on conjecture and possibly made by somebody staring at a wall and/or looking to make a humourous quip about a comment that doesn't meet their strict guidelines regarding the measurement of memory sizes. However, since such a quip is obviously based entirely on the flawed logic and an equal amount of ignorance regarding ISO and metric prefix conventions it is completely uncalled for and additionally off-topic to begin with.
