NAIPS and 64bit
Not sure about windows 7 but I am running 64bit vista and ran into the same problem with NAIPS not wanting to install under a 64bit OS. I got around it by simply copying the program files from my old computer directly into the program files on my new computer. Created a short cut to it and it works perfectly. The other option is to simply run it off a thumb drive in exactly the same manner as above. Works well especially when you don't take your laptop away with you as it saves aircraft, plans etc etc.
All the best, let me know how it goes with 7 if you try it as I'll probably upgrade shortly.