4GB SDHC Cards . . .

anyone have a decent explanation for this:

every SD Card & various Flash Drives I have use the entire space on the chip(s) in them
for the “partition”

however, every one of my SDHC cards don’t use the entire space,
disk management reports that they all have a 4MB unallocated space at the beginning of the “drive”,
is there any particular reason for this ripping me off of with unallocated space?

Is it safe to blast the partition and replace it with one that spans the entirety of the SDHC card or will that kill it? (x_x)