Of course your hard drive is faster when it has NCQ (but ONLY if the motherboard supports NCQ drives - and not all do!) and there is no problem with your PC queuing up several instructions to the HDD and executing them in the fastest way possible.
So - yes, an NCQ HDD is a must. Not because it provides speed improvements you can feel (it takes 10%+ to make an impact on "feel") but because it reduces (slightly) the big bottlenexk at the SATA port.
I would like to respectfully disagree. For the typical single user environment it won't help, and might even hurt. www.silentpcreview.com did some tests on the raptor, and found that it was better to disable NCQ. In the first place, a single user will rarely have enough hdd intensive tasks going at the same time to build up a queue of any length. And, if they do, it is likely because they are doing sequential work where the next read is likely on the same track as the previous. In such a case, with ncq, the cache may not be primed with the remainder of the track. If you have several sequential access type jobs, it will probably be faster to run them sequentially instead of concurrently. All this is theory, and only a test of the actual environment will tell if NCQ has any meaningful effect on performance.
I agree there are several reviews available through a Google search that can show you what he is talking about. Yes NCQ is a good feature for a server environment but it is not that useful for a desktop/single user. There have been several benchmarks that show better performance with it disabled. I would look but at the moment I am at a friends on a slow slow slow machine and any multi tasking slows this computer way down. It is a poor P3 . oh well rofl hope this helps you some.
I'm in the camp that thinks NCQ for the typical home user isn't an advantage. I have several raptors in hardware RAID all with NCQ turned off.
NCQ is like shopping for 100 items at a grocery store. It's a good idea to sort everything on your list before you gather everything in an efficient manner instead of wandering around the store in a zig-zag pattern. Why bother to sort everything on your list when you only have to run in for Junior Mints and Rice-a-Roni?
NCQ CAN be useful in certain circumstances but with today's apps and most single desktop user habits, it's not much more than hype and actually does more to slow things down than speed them up. All one has to do is read about it to find this stuff out. I guess the dude who thinks everyone here is nuts doesn't do any of that. The same holds true using AHCI drivers over the standard IDE. AHCI just doesn't at the present time take advantage of anything that will give the user anything useful in terms of performance increases.