There are many Linux choices for a HD install. Knoppix is not a good choice, but Debian, which Knoppix is based on, could be an option. The easiest way to try a few out, would be to get a few "live" disks together and give them a try. Ubuntu is probably OK, but I'm not always thrilled with it. I seem to go back to Debian, but have tried many of the distros that are available. Some of the Distros might not support your hardware well, and it would be easy to try the live disks and discover how they do. Here are a couple of good resources for information on some of the various distros and new releases.:

http://distrowatch.com/

http://www.linux.org/

As for the problem booting a few of the disks you have burned, it could be the media or a bad burn. It happens often enough. I usually recommend that the disk be burned at a slow speed, somewhere around 4X for CD or DVD. Some drives don't read some types of media well, so trying another type might be in order.

Another option when trying to access a Window$ partition, would be a disk like Bart PE, Vista PE, or Window$ PE, which are live Windows disks. They are usually able to read and write, with a lower risk of data corruption, to NTFS partitions. They support external media as well and can be configured on a network. They can be customized for various purposes. I use them quite a bit for Virus and Malware removal, along with disk imaging and data backups. There are a few other versions available as well. Microsoft has the PE disks available for download. You have to "extract" them from a larger suite of tools, but it's not that hard to do. There are a few versions available for Vista and Windows 7. Both of them should be somewhat backward compatable to XP. For Vista, PE version 2.0 works well. A quick google search will bring up a lot of options.

The L1 and L2 Cache that you have listed actually lives in the processor (CPU). It is the Cache memory for the processor and is a two level configuration. It is small, but VERY fast memory. It can't be serviced separately and the cpu would be replaced if it is defective. In your case, I think Harry had the answer. Sometimes the memory Dimms get a bit of tarnish between them and the contacts in the sockets. Usually a quick cleaning as he described works fine. Other than a memory issue, you could also have a hardware failure that is not quite as obvious. I've had bad chipsets corrupt data on drives. It's just not as common as memory issues. Somtimes it happens when the system heats up. Poor cooling on a laptop is a major cause of problems in some cases. Even using the laptop on a soft surface (Bed or Couch) that covers the cooling vents can have a disastrous effect on some machines.

I'm glad you were able to recover the data, since that is not always the case with drive corruption or failures.