Hmmm??

[PawNtheSandman]

I just installed a slave 200gb hard drive. It only shows up as 186gb in windows xp. Did I do something wrong?

[Xilikon]

Not really... HD manufacturers like to size using 1000000 as megabyte but the real size in the os is 1048576 for a megabyte.

[Ice Czar]

Binary vs Decimal Measurements (http://www.pcguide.com/intro/fun/bindec.htm)

in addition you loose a little to filesystem overhead
that varies with the fiesystem employed, but not by much

and not to open a can of worms or anything (like its going to make any difference)
according to the IEEE, the HDD manufacturers are correctly employing notation
the OS should be using GiB, MiB, ect for notation of space
SI prefixes (http://www.pcguide.com/res/tablesSI-c.html) are based on Metric (Tera, Giga, Mega) combining those with a binary system lead to the original confusion
and they predate their binary adoption in computer systems
http://lamar.colostate.edu/~hillger/dates.htm
(SI units formally adopted in 1954)