Vista - Vista displays incorrect hard drive space, keeps decreasing

I bought a new Dell about three weeks ago, which came with Vista home premium, 64bit, SP1. It has a 700 gig hard drive. I have maybe 45 gigs worth of anything on here, and it says I only have 553 free gigs. Every so often it drops a gig or so, and when I boot it up in the morning it's lost anywhere from 5-8.

I had my computer reformatted and it still isn't doing anything to fix it. Why is this happening, should I be worried, how can I fix it?

Hello DKwiggin,
Found a couple of sites that can explain it better than me. This may or may not be the problem, i cant think what else it could be, especially after a re-install.

Vista Hands On #16: A smarter way to manage System Restore space | Ed Bott’s Microsoft Report | ZDNet.com

Where's All My Disk Space Going? (Vista) - Notebook Forums and Laptop Discussion

Hope this helps.
Good luck and post your results,thanks.

In short, there are 2 reasons.

1. Your 700GBs you bought is decimal. In binary, the way the system shows it, that is 651 - which is still 700 billion bytes, just another unit.
2. For the time being you will "loose" at least 1GB each day (more if you install programs or updates). That will go on until 15% of your OS partition is reached. That space is reserved for the shadowstorage - the area where the system restore points are being kept. Once 15% is reached, the space will be reused (newest replaces oldest).

Bottom line, there is nothing to worry about.