I have an HP m400y. It came with XP Media Center 2004. My restoration discs are the discs that came with the computer. They only have two options (which are both just buttons to click): non-destructive recovery and destructive recovery. I tried both options, but even the destructive recovery left the partitions intact, it just restored all of the data on them to factory settings.

Just to clarify, the hard drive is 150 GB, and has two partitions, one 6 GB Recovery partition, and one 142 GB partition that now has only the OS installed on it. There is also 1 GB of unallocated space between the two partitions that is where the third partition I tried to create was placed originally. That extra GB was originally part of the Recovery partition, I think, because (if I recall correctly), the Recovery partition used to be 7 GB. I'm not quite sure about that because I never really paid that much attention to how big it was as I never had any intention of messing with those files.