[tacticalogic]

Of my 100 or so small business customers, maybe 20 have a Windows domain (defined as having a domain server that’s adminning the domain). The rest just have peer workgroups and *maybe* a file server.

Okay. That's customers. Do the ones that have a Windows domain tend to have more machines and users than the one's who don't? How about your medium sized business customers?

[Spktyr]

Other way around. Those with a Windows domain tend to have *fewer* users because the admin chores are actually worse for small businesses when they add a new machine.

Medium businesses are pretty evenly split between having a Windows domain, having *some* of a Windows domain (file shares and access controls but no AD), and having no Windows domain.

[antiRepublicrat]

Do the ones that have a Windows domain tend to have more machines and users than the one's who don't?

That would be a waste of money. More than a few users and MS screws you on the licensing. Even getting the OEM discount price at Dell when you buy a server it's $900 for 5 clients, $3,700 for 25 clients. For OS X it's $500 for 10 clients, $1,000 for unlimited clients (retail, not when purchased with hardware). Linux is free, unless you pay for support.

It's not hard to run 50 users on a modern high-speed 1U these days, and with Windows the licenses may end up costing you a large percentage of your total purchase price.