Desktop support can involve a range of staff at different levels of salary and expertise. To get a good average costing metric, we would recommend looking at all staff involved in desktop platform support (rather than applications, network, phone, etc) at your company and taking a weighted average for fully loaded cost (including salary plus benefits, expenses, office space, etc).
For example: say your office has five desktop support techs at an annual cost of $150, 000 each plus a senior technician who spends about half of her time working on desktop support issues and who has a fully loaded cost of $200000... you could calculate your average IT staff cost to be [5 * ($150,000) + 0.5 *(200,000)]/5.5 or $154,545
This spreadsheet assumes that the system is on and operational for the hours per week indicated above. For systems that spend a significant portion of the day in power save or standby mode, reduce the number of active hours used in the calculation to account for this.
To re-purpose an existing PC will require the replacement of existing software and applications on the device with a virtualization layer - either commercial or open source. This may include locating and installing the appropriate drivers to support hardware on each PC. We have estimated an hour per device for this process plus the cost of the re-purposing software if you are using a commercial solution. For a zero client, you will need to set up your connection profile once in the management console and then simply unpack and plug in the device at each desk. We have estimated 15 minutes for zero client deployment although some customers report timing themselves at under two minutes! Note that it is possible to simply install a VDI client on top of an existing operating system but this will double or triple annual platform maintenance costs (discussed below in 4).
We have made a very conservative assumption here that managing a repurposed PC will take, on average, 4 hours of IT time per year. This includes maintaining any OS and antivirus updates in the software underlying the virtualization solution as well as troubleshooting and resolving any hardware issues encountered with the device. Many sources estimate this number as being much higher... especially as devices age but even this very conservative figure should make clear the cost savings to be realized with a modern desktop endpoint. We have estimated 15 minutes per device for the zero client which should easily cover several firmware updates and re-configurations per year using the Management Console!
