First of all, I want to repeat the sad truth that while Knoppix can often read files on a Windows partition even when windows itself can't or refuses to boot, it is also quite posiable for Windows to destroy a partition so bad that even Knoppix can't read it. This may be your case.

But I'm wondering what is really going on here for a number of reasons. You don't say what was on those partitions that you can read but can't find your files on. And I'm wondering what partitioning you think was on your disk before you ever ran Knoppix. It's pretty typical for Xp to just be installed to one large partition on the disk, which would be called hda1 by Linux in this case. Alternately many OEMs now waste the customer's precious disk space by creating a recovery partition on the disk and not giving the buyer the actual discs that he need to recover and reinstall. But since these are also Windows partitons, one would expect them to be on hda5, the first logical partition. AFAIK windows will not normally let you have multiple real windows partitions on the disk, it insists on extra partitions be logical drives in an extended partition. Linux names the 4 real physical partition on the first IDE hard drive hda1, hda2, hda3 and hda4 and uses hda5 and above for the logical paritions. In this case hda2 might be the extended partition that contains logical drive hda5 (and perhaps others), but I have no idea why you have both an hda2 and an hda3. If you could shed some light on what you think was on the disk we might be able to help you better.