Your drive is not just having some higher speeds; its using DMA mode now which is a world of difference. As a result, you can also see the CPU utilization drop and you should have less issues with moving the mouse being choppy, etc.
However, your HDD may still be faulty. You have 1630 bad sectors that have been replaced with reserve sectors. That's a pretty large number; and the danger is that if it keeps growing, the harddrive will run out of reserve sectors and that would mean the disk has to be replaced.
You can check if this number (1630) goes up of if it stays the same. If it stays this number, there's no immediate danger to your disk. However disks can die quite suddenly, so be sure you have a backup elsewhere on another disk of the stuff you don't want to loose.
If i understand correctly, this is your system drive though, so some fluctuation would be expected due to background I/O during benchmarking. This can be seen especially due to the higher seek rates (the yellow dots) - in the last picture you posted these are more consistent than the picture before.