Best Hard Drive Diagnostic Software?

"... I need something quick, reliable, and accurate ..." ==>  Spinrite gives you 2 of the 3 (reliable and accurate); and is fairly quick on a good drive.   But if you want to thoroughly test a modern hard drive, it simply takes time ...  (i.e. "quick" isn't necessarily a good thing if you want thorough, reliable, and accurate)

I will check it out.  Are the results easy to read and understand?

In my opinion, the test diagnostics for a hard drive is the diagnostics by that HD manufacturer.

The 3 most common drive brands that we come across are Maxtor, Western Digital ans Seagate (who recently acquired Maxtor).  So my recommendation would be to use diagnostics specific to the drive.  Here are links to the 3 above:

Maxtor: http://www.maxtor.com/portal/site/Maxtor/menuitem.3c67e325e0a6b1f6294198b091346068/?channelpath=/en_us/Support/Software%20Downloads/All%20Downloads&downloadID=57
WD: http://support.wdc.com/download/index.asp?swid=1
Seagate: http://www.seagate.com/support/seatools/index.html

"... Are the results easy to read and understand? " ==> I think so.  But that's a loaded question;  it very much depends on (a) your own level of understanding; and (b) your expectations.   But it DOES test a drive more thoroughly than any other diagnostic you'll find.

This page has some screenshots (click on any screen to see a blowup):
http://www.grc.com/srscreens.htm

... One other comment r.e. your note that "... everytime I run scandisk, problems are found on the drive ..." ==> don't confuse disk errors with file system errors.    If Scandisk is finding surface errors, that's an issue with the disk;  but if it's finding file system errors, that's not necessarily a bad disk;  it could be a sign of some corruption in the OS (a bad DLL, a virus, an improper shutdown, etc.).   No disk testing utility -- no matter how good -- will resolve a corrupted operating system issue.

In your opinion will Spinrite, easily help me determine if a computer is running slow/erraticially due to a hardware related hard drive problem as opposed to a software related virus/spyware issue?

Sometimes I just run into a computer that even after a complete virus/spyware cleaning, and OS reinstall, the computer still runs slow and/or erratically.  Adding memory, tweaking performance settings, also don't seem to help, and eventually changing out the hard drive cures the issue.  I want to skip the long drawn out process of doing everything else I can think of first.  I just want a more definative way to verify a hard drive's heath, before telling a customer they need a part for their system.

... that's another "loaded" question :-)    Spinrite WILL let you confirm that the HARD DRIVE is working well => but there are other hardware-related issues that can cause slow/erratic performance:  intermittent memory issues; incorrect access mode (PIO vs DMA);  unstable power; etc.

But I would say the answer to your question is YES for most cases, assuming you're aware of these other possibilities and have either eliminated them (tested memory; confirmed transfer modes; etc.) or are confident they aren't the issue (assumptions aren't always a good thing !!).

... was writing while you were ==>  Spinrite definitely will provide you with "... a more definative way to verify a hard drive's heath ..."  [sic]

>>   In your opinion will Spinrite, easily help me determine if a computer is running slow/erraticially due to a hardware related hard drive problem as opposed to a software related virus/spyware issue?   <<  other than testing, you could simply swap in another disk to test the issue - this gives you a 100% proof if it is the disk or not.

In my experience, tests are good; but i still have to see a test with 100 % proof.
The ultimate proof lies in swapping devices.

SMART usually will tell you about electronic problems, heat issues etc of the disk, but it probably won't tell you much about surface errors on the disk. As has been mentioned earlier, I'd first use the manufacturer's utility to test the disk, These tools will usually be able to diagnose the disk enough to say it is bad or good. They usually output an error number which you then can use to RMA the disk so you'll get warranty. If necessary also use their "Lowlevel Format" utility.

If the manufacturer's tool doesn't find any errors and you still suspect the disk being bad, I agree with gary about spinrite. A further very good software, which can reactivate bad disks, is the Hard disk regenerator (spinrite can sometimes do that too, but the HDD Regenerator is better at that).

http://www.dposoft.net/

One thing to keep in mind, if you use the HDD regenerator (can take as long or longer than spinrite), it may repair the disk, but that is almost allways a temporary fix, as these disks will often get more errors. But it is a very good software as it doesn't change what is already on the disk, so you can make a backup after you have repaired the disk.

Is there a website, and/or a trial version?

CheckIt Pro is also a nice diagnostic ==> but I have to reiterate my suggestion of Spinrite. Spinrite is reasonably priced, and there is simply no peer for testing a hard drive.  I highly suggest you give it a try before using anything else (it's not free, but DOES have a "no questions asked" return policy if you don't like it).

I did buy and try Spinrite, but it was not exactly what I was looking for.  Does anyone know where I can get a trial copy of CheckIt Pro?

In the meantime I am using Hitachi's Hard Drive Fitness Test.

CheckIt Pro is a comprehensive diagnostic suite for the entire PC -- the hard drive tests are not as thorough as Spinrite or the manufacturer's diagnostics.  It does, however, give a nice Pass/Fail result (as noted earlier), so if that's what you're looking for it may be worth buying.   But the entire Check-It Pro suite fits on one floppy (including the configuration analysis code; tests/analysis for PCI, Plug 'n Play, DMI, SMB, Network Adapters, PCMCIA, CPU, PIC, DMA controller, Cache, Keyboard controller, CMOS, CD-ROM, Hard Drives, Floppy Drives, Memory, USB, Serial & Parallel ports, Video, APM, and burn-in testing routines).   It's nice to have all that on a single floppy, but it does limit the scope of the individual tests.

The hard drive test description reads as follows:

"    * Hard Drive Testing – CheckIt Pro utilizes intensive electronic sequences and test algorithms, at the sector level, to check the hard drive media for bad sectors and verify proper controller functionality."

It does do a nice test; but it's not any more thorough than the drive manufacturer's diagnostics -- and those are free :-)

hey Gary, can you do me a favor and have a look at this :  

https://www.experts-exchange.com/questions/21901860/strange-disk-behaviour.html

NOBUS: try changing your name to NOOB US!!!  What kind of retard posts a link to his post in the middle of another post.  Try sending an email if you want someone's attention.

Anyway I am still looking for a trial version of CheckIT Pro.  Can anyone help me out so we can close this question?  It's only been open for 6 weeks.

CheckIt Pro is not offered as a trial version.   They do, however, make the manual freely available for download -- so you can study the features and operation of it, and see if you think it's useful for you.  http://www.smithmicro.com/default.tpl?group=subcontent&id1=4&id2=197

I like it, but it's not inexpensive:  http://www.smithmicro.com/default.tpl?group=product_full&sku=CPRWINEE

You might want to try its "little brother" (CheckIt):  http://www.smithmicro.com/default.tpl?group=product_full&sku=CKDWINEE

mjirwin - thank you for your kind words !

Damn - I just looked at your profile, as much experience as you have on this site you really should know better, you're not even a noob, but you fooled me into thinking you were.

no problem, we all make mistakes. In fact it's from them that you can learn !