Worrying HDD Benchmark Result

Hello. Recently I have reinstalled Windows on my computer and since I have two hard drives, I thought it'd be a good idea to check their S.M.A.R.T. and how fast they are. I have one drive that has mysterious 100MB hidden system partition and the OS partition that I have created myself. It's a 120GB TOSHIBA MK1255GSH H taken out of an old PS3 console. I also have this 4 years old 160GB (Western Digital) WDC WD1600BEVT-60ZCT1 which is split in half - partition D:\ for my programs and partition E:\ for all my documents.

Now, I did a benchmark on both of these using free version of HDTune (2.55) the results were quite worrying
Here is the WD (D: ,E: ) drive: (Click here to see S.M.A.R.T.)

It's not fast but the read speed line is fairly stable.

And here is my Toshiba (OS - C:) drive, this is the one I am worried about: (Click here to see S.M.A.R.T.)

The read speed line kept jumping up and down like crazy, as far as I know, when it's that spiky, that isn't a good sign.

So, would any of you guys please have a look at my S.M.A.R.T. or the benchmarks and tell me if something isn't right?
Is that spiky line a normal thing on an OS drive?

Thanks :)

The "mysterious 100MB hidden system partition" is not so mysterious. It is a partition added during Windows installation to handle boot management functions. Do not change or delete it.

Thanks guys, your replies answer some of my questions, but not the most important one. The blue line on benchmark should smoothly descend (as far as I know) like on WD drive, or even smoother, instead it was jumping really bad, does that suggest there's something wrong with the drive? Might as well get a SATA III if my Toshiba fails :)

I think there is nothing to worry about those spikes in the graph. It just simply indicate that your drive is in use and much more active than the WD one. both drives are healthy.

Alright, thank you whs and Frozwire. I'll keep an eye on my drives though