So I am downloading a copy of 10.8 lion and I have snow leopard right now. But I am wondering if I can revert back to snow leopard incase something goes wrong with the lion copy I'm downloading. I am going to use a USB to Install it with as well. If you can help me that would be awesome
Yes, if you have the original discs, what you do is, make a back up before upgrading, then upgrade, and if you want to downgrade, eject the hard disk drive from disk utility. and then you'll be prompted for a cd, and put your cd in, and install the os, and then install your backup.
Downgrading is as easy as burning a new Snow Leopard Disc or Using a Snow Leopard USB, then installing by booting from the Disc and Formatting your hard drive Via Disk Utility. Also, 10.8 is Mountain Lion, not Lion