Did you put everything on one big partition?
You have to reinstall all your program files. Most programs keep the data they need to run in the registry. A no, you can not copy the old registry to the new PC.
For keeping important data, it should be on a separate partition if you have not done that already. If your program files are on a separate partition, just reinstall over the old location and it will keep your program settings/game save file. (you should still back these things up just incase).