Architosh has conducted a survey into cost of ownership for firms involved in architecture/building industry
you may want to have a look at some parts of it.

http://www.architosh.com/business/press%20information/pressreports/030604-aecreport-pr.phtml

snip>
Key Findings

There were five key findings in the report:
1) Mac firms spend on average 12 percent more on hardware costs than Windows or Mac/Windows mixed platform firms, 2) Mac firms have workstation replacement cycles of six (6) months longer than Windows firms, gaining a full year of additional productive use every two replacement (upgrade) cycles, 3) Cross-platform firms spend approximately the same amount on IT costs as Windows-only firms, 4) FileMaker Pro is the dominant database application used by AEC firms in the study, especially in cross-platform firms, 5) Macintosh-only firms spent 15 to 50 percent less on IT management costs (including staff type, staff hours, etc.) than both Windows-only firms and mixed platform firms.

"We were somewhat surprised by the findings," says Anthony Frausto, "especially the 12 percent greater cost Mac users spend on comparable hardware." "However, we were absolutely blown away with the IT management costs by Windows firms. Windows firms are clearly spending more money on IT staff related costs than their Mac counter parts."

Stephane Laroye, IT Manager at Hotson Bakker Architects, of Vancouver, British Columbia, Canada, a medium sized firm, said "this does not surprise me at all. The Mac is an intuitive environment so each user is able to comfortably figure things out on their own." He adds, "I can also comment on the fact that with Mac OS X, my IT time has been reduced considerably since we deployed our Xserve. With one disk image, I can configure all desktop machines the same while each staff person's Home folder is located on the Xserve. If there are any problems with one desktop, they can move to another and login into their own account giving the office far more flexibility (remember the mainframe days?)."

Even Windows firm participants commented on Apple's Macs being easier to maintain and support.
/<snip

and by the way in our industry you buy/use workstations, and most of the good CAD software is in the $5000-10000 bracket.

--
Gary Dorn
Permaculture architect
North Perth
[EMAIL PROTECTED]