Boot into the knoppix live cd as before
use the file manager to go to /mnt directory or whatever knoppix sets the mount points to/ use the command line to go there with
cd /mnt (or alternative)
Browse the files there and see what you can find, (ls if using the command line) see if your windows data is there. if not open a console and type
this will show you the partitions on your HDD, see if any have ntfs or fat32 as the filesytem
If you have no windows partitions there, then it looks bad, if you do (fingers crossed) then you just messed up the boot record on the machine, and it doesn't know where to go to boot the operating system.
Ok so you have found that the data is still there (hooray) now you need to fix the mbr (master boot record). This can be done easily by inserting a fully fledged windows cd and following the comands to the rescue console, once there run the command fixmbr and you should see text indicating it's working.
once done reboot the machine and it should be ok
I have tried to do that as simple and clear as possible, if you have further problems we can work through them
Does knoppix not use a graphical partitioner?? what version are you using?
ext2 is being replaced by ext3 now (journaling features)
Once you get it fixed and are ready to try again (dont be disheartened, happens to us all) use the knoppix cd to add a SEPERATE partition (maybe you did this in knoppix install), for playing around with linux, look into fdisk to achieve the partitioning.