160GB HD seems excessive, what do you plan on installing and running on that unit?
I plan to run XP. But, the prolog to your question requires a much longer explanation.
The fact is I generally buy the drive with the greatest capacity I can afford within my budget for that computer. Why I do that takes some understanding of computer performance in general, and HDD geometry in particular. (I have some professional expertise in both areas. I will spare you my lecture on the importance of the HDD to overall system performance.
As your question suggests, it is unlikely I will use even one quarter of the space. The drive in question goes for $55 at NewEgg. It is a new drive, with a 3 year warranty. That amount was within my budget for upgrading the 390X.
The drive under consideration has a specified seek time of 12ms and latency of 5.6ms. If I could alternatively get a 40 gig drive for (say) $40, with identical seek time and latency, the question then comes down to whether an extra $15 is excessive. Or, maybe I could do a lot better by buying an old-tech used drive on eBay with the same specs?
Assuming a new drive, why throw away even $5 for space I will never use? That question is based on the assumption that the only thing that matters about HDD is space. Why pay extra for more space than you need? Indeed.
What many people fail to understand about large capacity drives is that they provide much more than capacity. In particular: The greater the capacity of a drive, the greater the recording density. The greater the density of a recording medium, the less time it takes to access a unit of information. IOW, capacity = performance. Seek times and latency are handy, but give a false impression to many. Drive capacity is super cheap today, which makes for very interesting performance equations.
Latency is simply the time for a half-rotation of the spindle, so is the same for all drives of a given number of RPMs. All 5400 RPM drives have a latency of 5.6 ms. I would not put a drive with greater RPMs in a laptop not specifically designed for it, because of vibration. So, 5.6ms latency is pretty much a given for the 390X. However, it is highly likely that the next unit of information you need immediately follows the last unit you read, so the greater the amount of information available the more data. Higher capacity drives have more data per rotation, hence, faster average access time. The 8MB cache on this drive improves that even further. Not to be had on older drives.
The specified seek time of a drive is not a constant like latency. It is based on using the entirety of the space reachable by the head. My guess is that most computer users have a system partition that comprises the entirety of the HDD, which makes these seek times reasonably accurate because Windows allocates space from both ends. However, I do not partition drives that way. What I will do with this drive is create a 12GB C partition on the outermost tracks of the drive. 12GB is more than enough to run XP and the apps I have in mind. If an average seek over the entirety of the drive is 12ms, what is the average seek time over 7.5% of the drive capacity? Not as easy a question to answer as it looks. Consider first that the arm will travel less distance than 7.5% of the drive surface because there is more information on the outer tracks of a drive than the inner tracks. (The circumference is greater) Second, you need to break down seek time into constituent parts to understand how much of the 12ms time is travel time, how much is just overcoming inertia, etc.. I haven't done the necessary testing to determine this precisely, but all in all, I would be surprised if seek times in the resulting partition exceed 2ms.
Bottom line: How much price differential would you consider "excessive" for a drive with 2ms seek time versus one with 12ms seek time? I could get a 250 GB for about $30 more, but that is about it. In this case, the Samsung seems to be at the "sweet spot" for my 390X, given my budget.