[dba-Tech] Most used software

I want to ask this question twice:
1. you (a presumed software developer)
2. your clients

I realize that there might be an overlap, and am not sure how to handle
that but I'll get to it eventually. Meanwhile, let's assume these basics:

a) since I'm addressing this audience, I assume we can skip the Windows v.
Linus argument, and instead assume that the OS answer is Windows, which
leaves only Which Version?
b) I'm guessing (no reason) that most of your clients are using various
Office apps, and that perhaps so are you. But no Guarantees! For example, I
have chosen Chrome and gmail over IE and Outlook -- not I'm not after
agreement but rather numbers, not from some large measurement-entity out
there in the wild, but rather from right here in my more immediate
community.
c) This might also involve your use of various VMs, which would beg the
question of How much time and in which?
d) At this point it gets much more general, but I need to ask this
question: how much time do you spend on maintenance, by which I mean such
mundane tasks as Backup, Defrag, burning backups to more permanent media
such as DVD, installing Windows updates and various patches to subsystems
such as ADO or FlashPoint updates, (this list could go on and on and on and
on, but I assume that you get the point), and so on?
e) Do you factor in any of the expenses in category d) into any and all of
your billings to each and every client, or do you simply absorb all this as
the cost of business? And if the latter, do you add some percentage or
fixed amount to the billing to each client, under some general title such
as "Administration"?

I'm not challenging anyone's particular method of handling this stuff. Far
from it. I'm researching how freelancers deal with this stuff, and perhaps
in this light, hoping to learn a trick or two.

-- 
Arthur
Cell: 647.710.1314

Money never arrives at an inpportune moment.
-- Don't know who said that first, so I'll claim the credit.