I had a restore partition on my HP Pavilion dv5 which I didn't want or need to see. I this is what I had to do to hide it.

This is suppose to work on Windows 7, Windows Vista and Windows XP

Start > Run > diskpart and hit the enter key.

In diskpart type list volume

If you want to hide D: drive it was volume 1 for me.

Type select volume 1

Type remove letter D

Restart and the drive in hidden

To restore:

Type select volume 1

Type assign assign letter D

Found the information at http://cyberst0rm.blogspot.com/