Brian V wrote:
Inside my computer tower is one hard-drive. But I have two in my
computer. It is like the drive is seperated into a C: and D: drive.
Why is this? Can I rejoin them? If they were split, does it take away
from the amount of space there is there (say it's 400gB would this
situation make it 350Gb one has access to. The other 50Gb being a
buffer of some kind?)?

I will assume a few things, so please correct me if I'm wrong.

1. You have a PC that contains one hard drive and when you open My
Computer, you see two "drives" (these are actually partitions) listed,
namely C: and D:.

Some PC manufacturers (Sony, for instance) pre-configure the hard drives
so there are two partitions. C: is meant for the operating system and
all it settings and updates and also for all your installed programs,
including all their settings. D: is meant for all your data: your word
processing doucments, spreadsheets, music files like mp3s, videos, etc.
The PC manufacturer could have just as easily included only one giant
partition, which would contain *everything*.

Why do certain manufacturers do this? Perhaps there is a restore program
that will work quicker if the system partition isn't too large.

You can only rejoin them by using a third-party disk partitioning
program like EASEUS or Partition Magic. But you might decide you like
the default layout; there's nothing wrong with it and there is some
logic behind it. That is, you might be satisfied leaving well enough
alone.

In addition to these two visible partitions, it's possible you have
other *hidden* partitions. They can be seen by using the built-in
Windows program Disk Management. Some hidden partitions are relatively
small and contain diagnostics. Others are fairly large and contain an
image that cean be used to restore the PC to its original condition.