This is a common misunderstanding; I got confused the first time I ran these tests, too. But there's nothing to worry about; despite the scary-sounding terms, the results are totally fine (don't believe me, though -- read the "Assessment" column and the test summaries at the top of the window).
The "Worst" column simply lists the worst allowable value for that specific test, and has nothing to do with your hard drive's actual results (which are all good -- again, see the "Assessment" column next to each test).
Likewise, "Pre-fail" and "Old Age" in the "Type" column simply tell you what kind of test it is -- those terms don't say anything about your hard drive unless it actually failed one of those tests (which it didn't).
If you want to see what the results window looks like for a drive that actually failed a test, see this question: Read Error Rate is more than 5000... Do I need to replace my Hard disk? ... notice the big, red, bold SELF-TEST FAILED message.
But your results show that your hard drive is totally OK and there's nothing to worry about.