As far as I see it, if you boot winblows or you write a file, you will leave fingerprints.
As an alternative, you can download Konboot and boot from it. It will hack the system login to accept any password you type in. It works with both XP/Vista, not yet Seven. Then, review/clear logs and restore the original SAM.
You can, of course, boot linux (or Clonezilla) from RAM, clone the disk (dd command will do the job), play with it, and then restore de byte copy if you are really into it.
By the way, did you test the last script from the other thread?