System Restore With default settings, it may take upto 10% of ur drive space.
Swap File with default settings, will take 1.5 times of your total RAM.
Hibernation Support will make a pagefile in ur system drive as big as ur RAM.
Check if you have any of these files. Also some temp file may be created while you are using some applications, thus eating space.
With SequoiaView u should get diagram like this tell what files u taking how much space. Each rectangle is a file on disk. Just hover ur mouse over rectangle to see the filename in tooltip. Other info about file is displayed at status bar.
make sure to select Show hidden and system files in options to view all files.
Here is what u should get
*img233.echo.cx/img233/5185/screenshotsequoiaview7vd.th.jpg
Get it from *www.win.tue.nl/sequoiaview/
Larger the rectangle, larger the file.
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