I don't think you're going to recover files from a RAID 0 system based on Windows only software RAID drivers with Knoppix or any Linux system. If it's a hardware RAID system you should be OK (more or less, although RAID 0 more than doubles your chance of complete data loss), but most people who post here with RAID issues are using software RIAD solutions. While Linux does have some RAID software, it's not likely that the drive geometry would match exactly, which would be required for proper file recovery.

While you may think that you can see files when you look at a drive with Knoppix, you're only seeing the directory blocks, and Knoppix is assuming that the data is only on one drive, not spanning both drives. It's looking in the wrong place for the actual file data.

Your best bet, if it is a software RAID system, would be to install XP on another drive on a different IDE connection on your computer (even if you need to add an IDE interface) and then install the RAID drivers and try to access the RAID array as a second drive.