
Thank you Beastman, for confirming I'm a nerd.
You can download SuperDuper! (for example) from here for free (although it'd be nice to donate to the developer):
http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html
The site explains a lot. If your hard drive should ever bite the dust, you'd be able to boot right off the external drive as if it were your actual machine, use all your software, etc. When you copy your files to another hard drive randomly, they're not bootable. --Or your entire Mac tank, you could take your bootable drive and connect it to another Mac and work on it like it's your own machine. CCC & SD! make it soooo easy.
Partitioning just means you're dividing your hard drive into sections. Like a bootable clone in one, a scratch drive in another, random files in another, etc.
Please consider setting up Time Machine after (or before!) installing Snow Leopard. It's so easy too, that if (IF) something should happen to your Mac in future, well, why bothering kicking yourself in the butt then if you can set it up now practically effortlessly?
Regarding the refinements in SL versus Leopard, --can't think of them off hand except the Mac App Store. I hate shopping, but damn, I do love looking at the Mac App Store.
Another thing about using Time Machine, I used it from another iMac when I set up my new iMac. All my applications were installed, like MS Office & Adobe Creative Suite, and I didn't have to re-enter any user registrations, etc. Saved so much time!