Missing Half HDD ?

reformated and partitioned 14g hard disk.
fdisk display showed 2 x 7.g. active drive
1 x ext dos drive
installed win98
my computer right click C:/ properties =7.g
right click D:/ properties =3.5.g

so i reformated and chose y to large access in f/disk
created active 14g drive
installed windows98.
my computer C:/ properties =7.5 g!

why is windows miss reading the true size of my hard disk?
many thanks