Secret Sector Backdoor / Security Breach

Hello everyone,

Recently I've realized that Windows XP Pro (SP1) secretly writes data

to hard-disk sector(s) that were beyond its installation-partition

boundaries

at that time I used a basic Windows XP installation on a 3-GB

partition,

and the rest of the harddisk was unformatted, for all Windows cared.

I should also mention that my WinXP partition is formatted on FAT32,

but I am capable of accessing NTFS partitions, if need be, using

NTFS4DOS,

(which I didn't).

Obviously I was only able to have discovered that with an MSDOS-run

Disk Editor

capable of accessing all 160 million sectors of my 80GB hard disk, and

making

a text-based datafile containing sector numbers (Cyl., Head, Sector +

Index),

that was runnable under pure MSDOS mode avaiable by booting

from a BootCD / BootDVD.

I wasn't quite sure what the nature of that data was,

and whether or not it was a copy of the swapfile

(e.g., PageFile.SYS), or some other data off RAM,

or maybe password(s) or other sensitive data

that I may have been working on prior to re-booting

from my BootDVD.

So my questions are:

1. Would anybody be familiar with that sector-writing stuff?

2. If so, what is the nature of the data written?

3. Would password(s) typed at MSDOS-based program(s), run within

Dos-Box windows, be secretly saved there too?

4. How Am I do prevent that from happening?

5. How Am I to erase such data?

Thanks much,

SCU