leave your registry, don't ever move that, all your documents you should move to an external, compress them first so they take up less space.
You can't just move a program, you have to reinstall it on the new OS.
You can always create a new partition for the new OS, and once its installed, you'll be able to access the partition w/ the older OS, and just copy your documents directly over. no middle man.
Once everything is copied, just delete that os (and remove it from startup in 'msconfig') and expand the partition to the whole drive again