Cannot find missing 30GB after XP Reinstall

Hi,

I have just reinstalled Windows XP SP3 Pro after a Stop C000021a error message wouldnt
let me boot up. I believe that there was XP Home edition before, but it was still
formatted in NTFS. During the installation, the setup told me that in order to reinstall
in the same folder C:\Windows, the old windows folder would be deleted. I said that
was okay and continued.

Fast forward until all was done and XP is running beautifully. My C: drive has about
70GB total, and 20 free. When I select all and look at the properties, it calculates
the total files as being roughly 20 gb. The other 30 GB of data I had from before
are no where to be found.

Has anybody had this problem or know of any way to figure it out. I would really
like my old files back, and they are there somewhere, I just cant find them.

Thanks for your help.