Kevin wrote:
> I'm looking at buying a new Hard Drive with about 4 or more Gigs of space
><snip> I am looking for a short explanation of the
> current and soon to come technologies and how they will effect my current HD
> which I will set as a slave to the new one. (NOTE: The new HD will be used
> to run Win95/98, WinNT and Linux.)
 Kevin, there IS no "short explanation" - Entire books have been written
on your questions.
 An intro: (quote)
For the average person who is using their PC for light office work,
games, internet use, etc., I still recommend
IDE/ATA. The reasons are simple: cost and simplicity. Virtually all PCs
today ship with IDE/ATA hard disks
standard, and if you are using a small number of devices--say one hard
disk and one CD-ROM drive, IDE/ATA is
more than adequate performance-wise for the typical office or home user.
As long as the machine is reasonably
modern and the PC is set up properly, IDE/ATA will work without much
difficulty, and there is no need to
special-order or customize the machine, since it is really the
"standard". The cost of a simple IDE/ATA setup is far
less than an equivalent SCSI bus.
For the user who is performance-conscious, who will be doing real
multitasking, using many devices at once, doing
heavy development work, supporting multiple users at once on the
machine, or who otherwise wants the best and is
not afraid if it costs a few hundred dollars more, SCSI is the obvious
choice. SCSI offers the most flexibility, the
most choice of peripherals, and the best performance in a multitasking
or multi-user environment.
 (end quote)
This was excerpted from: http://www.pcguide.com/ref/hdd/if/comp.htm, an
excellent reference.
For my slightly-tired 486 I purchased an Ultra33 controller, with
excellent results. Here is excellent advice from http://www.Promise.com
: (plugging their own stuff, of course - but there are numerous other
good suppliers)
     1.Purchase Ultra ATA/DMA drives that have over 5000 RPM and a low
access time (less than 10ms). This has a
        significant impact on data transfer rates and processing times.
Use an Ultra ATA/DMA controller that supports the full specifications of
Ultra DMA/33 including 33MB/sec burst data transfers and CRC
error-checking at higher transfer rates. Many of today's motherboards do
not fully support Ultra ATA drives.
     2.Use two drives linked as a single drive and access both drives
simultaneously to double the read/write rate. Promise FastTrak links up
to 4 Ultra ATA (minimum 2) drives on two separate data channels
sustaining up to 25MB/sec data transfers.
     3.Use a separate drive for video editing capture/playback or any
application with a large continuous data stream. Be aware that with most
controller/drive combinations, the outer tracks of the drive will
generally write data faster than the inner tracks, so use the first part
of the drive to save video files. Note that the Promise FastTrak
controller assures that the  read/write from inner to outer track is the
same while supporting the fastest video capture cards.
      4.Add more IDE ports to your system. Attaching an IDE (ATAPI)
CD-ROM drive to a separate connector from your
     hard disks prevents slowing drive performance to achieve concurrent
data transfer. Hard disks have a higher data
        transfer rate than ATAPI peripherals. Ultra33 offers two
additional IDE ports to a PCI motherboard freeing up the motherboard IDE
ports for these slower peripherals. In addition, make sure that the
controller you use employs
        separate device timing like Ultra33 to allow slower and faster
drives on the same channel.
     5.Avoid using disk compression programs. These require both CPU
utilization time and also slow down disk access.
     6.In Windows Control Panel, System Tab, be sure that 32-bit Disk
and File System is enabled.
     7.Enable Read Ahead Caching for hard disk and CD-ROM drives except
for video-editing applications.
     8.Schedule a disk defragmenting utility program to run weekly to
fine tune the disk and to reduce fragmented files that will slow disk
access.
     9.After a system lockup problem, run a disk repair program after
reboot to check disk integrity
    10.Create a swap file on a drive separate from the system drive.
(end quote)

 Most HD makers have fax docs, and/or websites, and snailmailed data
pages free for the asking. Western and Maxtor had excellent info., last
time I looked.  Beware of purchasing the cheapest drives, even from
recognized manufacturers.
Sorry this was so long, but it's good advice. Happy researching,
Dave Ross
San Francisco