Why wont my Video Card display 32 bit?

I just repaired a PC and used "used" parts including the hard drive which had XP Pro on it. Before i reformatted the hard drive the graphics were fine (at 32 bits) but when i put windows ME on it i only get 16 bits. Why is it doing this???|||You need to get the correct driver for your video card|||you need a graphics driver. You can download them from the net.|||check ur video driver|||maybe your settings on your computer are nest up you should check if you install it right