Not quite sure how to get you out of this mess, but it's a salutary reminder not to dive in too quickley when given options that you're not sure about. If hal.dll was all that was needed you could have downloaded it from click here
Also what you should have done was to boot with the XP disc and gone through the process to repair your Windows installation, not install it again. You can try doing this still, but be careful. Do not use the Recovery Console (This also offers the option to repair, instead press Enter to go into Windows Setup. It will search for installations, select the one you want to keep and press R to start the process. Hopefully Windows will install over itself and you should be ok again.
What you do with the unwanted installation is anyone's guess. I suppose you can just delete it.
Then fit another gard drive and install imaging software, and backup regurlarly.