What's taking up so much space on my hard drive?

What's taking up so much space on my hard drive. I just bought a new Acer vista computer. It says 37 GB of my local hard drive is used up! I don't even have many programs or files installed. My computer is a week old. I don't know what's taking up so much space.

So I open my hard drive (C:) and the break down is (including hidden files):

Windows 9 GB
Users .5 GB
Program Data .2 GB
Program Files 2 GB
MSO Cache .3 GB


Total should be 12 GB instead of 37 GB. I don't get it. Anyone know why?



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Update: Did some reading.

I will try:

Disable System Restore, delete restore points, run CHKDSK.

I also found this useful forum: http://forums.cnet.com/5208-12546_102-0.html

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Update: It worked. My used space is 14GB now. 2 GB used by hibernation function.