This depends on your situation; if your computer is more than four years old,
chances are that most of the parts will be too old, slow or incompatible for
your new machine. On the other hand, if you are upgrading from a fairly new
machine, you may be able to use many of the parts. All of this assumes the old
computer will no longer be used. If you, or someone else, is going to continue
using your old computer, it’s probably best just to leave it intact.

One important point if you are selling your old computer it’s a good idea
to erase the hard drive before giving it to it’s new owner. Special precautions
must be taken to ensure that you are not giving away your sensitive or personal
information. Don’t forget that a simple ’delete’ command does not actually
erase the data on your hard drive. The original data will still be present and can
later be recovered by someone else using special programs and/or equipment. To
avoid this, programs are available that will effectively ’shred’ your data, making
it unrecoverable. Driver floppies or CD’s that come with some hard drives may
also have programs to do this, that write 0s or 1s (either way, “blankness”)
to the whole drive. Lower-tech approaches include running a speaker magnet
around the hard drive a few times or drilling a few holes in the drive. Obviously,
the latter prevents it from being used again.

Since monitor technology moves quite slowly, you can probably keep your
current monitor and use it on the new computer if it’s of sufficient size and
clarity for your work. The same can go for keyboards, as well as mice, printers,
scanners, and possibly speaker sets. On the inside, you may be able to take out
the floppy drive, CD-ROM drive, and possibly the sound card and hard drive
(depending on how good they are, of course). Sometimes so much is used from
the old computer, that the line between an upgrade and a new computer can
become blurred.

Reusing a hard drive is an easy way to keep data from your old computer.
With most Windows operating systems moving a boot drive from one motherboard
to another will entail a series of reboots and installation of new drivers.
In the case of newer Windows systems, like 2000 and XP, an entire ’refresh install’
may be necessary to allow Windows to install a new Hardware Abstraction
Layer. Back up your data before trying this.