Hi Brendon - and thanks for answering my post!
I'm using the original, downloaded "Part 1" and "Part 2" files but, significantly, when I've gone to check out AppData there is no Roxio folder!
So, I've used WinZip to extract all of the files and that folder accords, exactly, with yours! However, even knowing where the program is launching from, it still falls over when attempting to read the NXT3.msi file! So, I'm stumped, once more!