Error Checking in XP

If I go My computer > Select some drive > right click > click 'Properties' > Tools (tab) I get 3 choices: Error check, Defrag and Back-up.

I ran the Error check on my slave drive. After a while it said "Disk Check Complete." That was ALL it said. Was it checking the disk for corrupted sectors or what?

Next Question: What is it Backup is supposed to back up and where and how?

Error checking is similar to scandisk from win9x and 2k etc... not sure of the level of scanning, perhaps just a quick file scan, but should be options somewhere to invoke full surface scanning etc...