How much faster are SATA hard drive than 'regular' hard drives.

I imagine hard drive speed is demonstrated in the speed of opening
applications and large files. Is this mostly where you see performance
difference between the two?

Thanks for all comments and help in advance.
Patrice

Refer to http://pcburn.com/article-Linux_SATA_vs_IDE_Performance-pg6.php
As per this test, performance was not noticebaly good.

These days, the interfaces on drives are much faster than the physical
medium can provide to (or consume from) them. i.e: If the heads inside
the drive can only handle 50megabit/s of data, it doesn't matter if
the interface can do 100 or 150megabits, you'll still only get 50mb/s
worth of data.

Think of it as the equivalent of having an 8 lane superhighway with
semi-trailer loads of data going back and forth, and then having to
unload and have a horse drawn cart drag the data over a dirt path for
the last mile.

That being said, SATA (serial ATA) interfaces are capable of higher
speeds than the older PATA (parallel ATA) models. However, interface
speed is not the only metric, as platter size, number of platters,
rotational speed, head seek time, cache, chipset, and chipset firmware
all affect speeds.

When it comes to speed, the difference between PATA (the old ones) and
SATA is relatively small. However, SATA offer many other benefits like
longer cables, hot-swappable drives (you can plug them in and out
while the PC is on), they usually ship with large buffers (8 to 16MB)
and many motherboards come with and SATA RAID controller by default
which, if you have to very similar drives, can allow you to increase
their aggregate speed (RAID-0) or help minimize data loss when one of
them fails (RAID-1).
Check out the Hitachi drives, they're usually the fastest :)

There are two major versions of SATA. SATA 150 and SATA II, SATA 150
was the first version of SATA to come out, compaired to the
performance to a IDE is almost neglible(IDE is 133 M/s SATA 150 is 150
M/s). If the Spindle speed on the SATA drive is however 10k RPM(WD
Raptor SATA Drive), then it would be faster, and better performing.
The newer SATA II has a data transfer rate of 300 M/s, allowing  more
data to be sent between the hardrive and system. However, speed of the
spindle is still what affects performance in the long run.

Let's not forget the bus bandwidth bottleneck as well. :)

On a PRACTICAL basis, the difference in the interface apparently won't
matter that much.   I have some geek friends who were recently
discussing that even using solid state hard drives, that Windows XP
didn't load noticably faster.  With the large cache sizes, and as the
other folks have stated (marcbb-ga's explanation was a great analogy),
so much of the speed impact being physical attributes of the disk
(like rotational speed) -- you might be better off focusing on issues
like warranty, reputation, user feedback, etc. when purchasing a
drive.  You need SATA, as I understand it, to set up a RAID setting --
but if you just want to use the hard drive stand-alone, then an IDE
ATA drive with a big buffer and the best cost per gig, along with a
good reputation, a long warranty, and good user feedback from a site
like Newegg.com is going to be a very reasonable strategy for a
typical Windows user.

So the next question should be: What performance increases could you
expect by using 2 SATA drives in a RAID 0 configuration?  Let?s assume
the drives are SATA I and those operate at 7200rpm.