Downgrading from Snow Leopard?

John Carter has been plagued with several problems with Snow Leopard. He says, "The interesting part is that the problems are isolated to my login and the problems did not show up in another login. However, in the process of trying to resolve the problems with my login, my iMac no longer allows me to login as any user. These problems are quite unique to my computer and may not happen to anyone else."

As a result, John needs to downgrade his computer back to Leopard and then restore all his applications and data from his Time Machine backup to the date prior to upgrading to Snow Leopard.

He warns, "If you are not keeping frequent backups of your computer, you may not be so lucky as to restore to a known good snapshot."