Boot from CD, make backup, reinstall snow leopard. Good idea?
Booting from an install media such as a Snow Leopard install DVD will not boot to your desktop. Instead, it will boot to the OS installed on the disc and whilst this is OS X, there's no Finder for you to move files around.

However, the disc does come with Terminal and you can use it to copy your files to somewhere else, another disk, etc. There are numerous tools that you can use in Terminal to copy files, but for individual files/folders as mentioned in your question you can simply cd /path/to/original /path/to/location to copy them.

Then, using the disc, reinstall Snow Leopard and copy your files back once booted back (using the now-available Finder).