Quote Originally Posted by Orion6
I have hda1, hda2, hda5 and hda6.
Again, not typical. hda1 and hda2 are both real physical partitions, which is not typical of Windows, generally Windows will only let you have 1 physical partition and makes you create the rest as a logical drive in an extended partition. This may be something strange that HP did, but seeing that as well as 2 logical partitions is certainly something that I have not seen them do before.

Quote Originally Posted by Orion6
hda1 is my missing partition and it seems to be accessible from knoppix/Linux. I just can't figure out how to relabel it as the C drive. I'm pretty sure evertthing would work okay then.
You absolutely should not try to change this partition with Knoppix. If Knoppix can see it then the MBR is correct, and Knoppix should not be used to write to a NTFS partition itself. (Think about, if Microsoft can't even write to NTFS partitions safely [and we see plenty of proof here that they fail to on a regular basis], what are the chances that Linux could improperly write to this proprietary format? ) I suggest instead that you consider yourself very lucky that Knoppix can see the data that you want and that you make yourself good backups of whatever you want and then freshly install Windows on your C partition (assuming that you still want Windows). There are many ways to back up your data with Knoppix, my personal favorite is to install a FTP server on another system and then use Konquror as an FTP client to transfer the files to it across a network (but do whatever works for you). Writing to hda1, if you can manage to do it, may very well be the final nail in the coffin and destroy your last chance at data recovery, it is not safe even when Windows thinks the partition is good, let alone when it seems to be bad.