If you want to know what is consuming how much on your drives, check out TreeSize Free. It is not too elegant, but easy to figure out.

TreeSize Free is freeware for Windows 2000/XP/Vista. Users of Windows 9x/ME can download last compatible version, V2.1 from same page.

aww, with christmas getting close, i thought you were asking for advice on literally tree size
nah, that looks good, im gonna try it, my hard drive has bit mysteriously vanishing recently :O

PCMag used to have PieChart but now you have to pay for it. But this is easy to use.