Is it better for me to buy two 4-door sedans, or one SUV?
Noone can answer either of our questions without context! It all depends on
what we're looking for, determining what we intend to do with these items
before anyone can even attempt to suggest "what is better". If I told you
my wife and I both need transportation, what would suggest? Suppose I added
that we both work in the same location with identical work hours, what then?
Suppose I told you we like to hit the off-road from time to time, the
"outdoorsy" type, what then? Context is EVERYTHING!
So which is better, two 40GB HDs, or one 80GB HD? Beats me, what do you
intend to do? Suppose you intend to mirror your data to protect it? Well,
I strongly suggest using two 40GB HDs since any RAID configuration requires
at least two HDs. On the other hand, if you don't need RAID, a single 80GB
HD is probably going to cost LESS than two 40GB HDs (is price a factor?).
And statistically, the more drives you have, the greater the chances for any
one of them failing. So if you intended to strip them (as in RAID-0), you
increase the chances of lost data (when one HD in a striped array fails, ALL
data on ALL drives is lost!). You may also be using an older motherboard,
perhaps limited in its ability to "see" larger HDs. If so, you'd have no
choice but to use two smaller HDs rather than one large HD (or else use a
PCI controller card, assuming you have PCI and a free slot). Or suppose you
wish to backup your HD from time to time, that's certainly not possible w/ a
single HD. Or suppose you wish to keep the OS on one, your DATA on the
other. This allows you to optimize each HD independently, which isn't a bad
idea, since the contents are quite different, and therefore require
different considerations as to partitioning (size, file system type (e.g.,
NTFS, FAT32)), type of backup, how often to backup, or whether a backup at
all(e.g., a HD with only the OS may be expendable, your data on the other HD
is NOT!). Or suppose you wish to dual boot at some point, it can make
things easier at times if you keep each OS on separate drives, perhaps
shuffling between each w/ a mobile HD rack. This is especially true if one
the OSs is Linux (which, for reasons I won't elaborate here, is a little
easier to manage when it has the HD all to itself).
So without context, without *some* idea of what you intend to do, what you
can afford, what your expectations are, there simply is no answer to either
of our questions.
HTH
Jim