Will a clean install of Snow Leopard delete my user files?

I would suggest using Carbon Copy Cloner to create a disk image of your Tiger disk on another drive. Then do a fresh install of Snow Leopard, but when you're setting up the first user, create a dummy user. Once you've done that and are logged in, mount the disk image by double clicking on it and start the Migration Assistant in /Applications/Utilities/. The Migration Assistant will recognize the mounted disk image as your previous system and pull in whatever you want from it. Or you can just copy back what you want from the disk image without using Migration Assistant, if it's just your documents from your old profile. Lots of options. :)