Initially, we had the same experience as others:
"I bought a turbotax cd and download/installed in a macbook; after that try download into a window laptop, turbo tax message that: the code already in my account, it not let me to download again"
Here is what WORKED for us - Set up a NEW, separate TT ACCOUNT for the windows computer, and then installed the program with the disc, using the same code included with the CD (it may have worked as a download at that point, too, but we didn't try that so can't be sure). It worked fine after that.
