Sorry to but in on this thread but I have a similar problem.
I've sorted a lot of my family tree and greatly appreciate the help from the good folks at Rootschat, but my cousin has more information which we can't access.
She last worked on it in about 2005 as far as she can recall but her file is saved in .gft format, she changed to a mac a few years ago and no longer has her old PC.
She also can't recall if she had the CD for GSP Family Tree or whether she purchased it online and downloaded it, either way we can't get our hands on the software to open the file.
She's happy to buy the software again or at least buy some software that will open her file, but Google tells us that such a beast is not available.
Any help we can get would be very much appreciated.