You mileage will vary
I was forced into implementing thin clients a few years ago, using Terminal Services (well, more properly, Remote Desktop Services - Server 2008R2) and it was a nightmare.
We didn't have many users 15-20 so the scale wasn't there, no particularly standard desktop (small company with everyone doing different tasks), no expertise in server config (for the life of me, I could not get the desktop locked down to - e.g. - limit access to control panel but allow users to change wallpaper - a big thing in small companies with staff at reasonable levels of seniority), we could afford one server so we were always going to be one hardware fail away from bringing down the whole office. The HP thin client devices we had were underpowered so display sizes were poor and screens lagged. Replacing them with half decent clients was (as someone else pointed out) the price of a half decent desktop each. We also had to pay MS for RDP licenses for each user on top of the standard Office, Server and Exchange CALs.
Over the course of the life of the system, we *may* have saved on power usage and a little less in AC for cooling an office not filled with hefty PCs but it would be minimal. Support was a PITA and and the server came in at around £6k - all that RAM! Users hated it and felt like second class citizens - they all now have Windows 7 desktops which, yes, need a little more care and attention, but some things are worth it.
Needless to say, the idiot that insisted on the system had for himself, a nice and shiny, thin in build, but very fat in spec, laptop. Some users are more equal than others as we know.
This has turned into a rant - I apologise. I know that a thin client system can work and is indeed, preferable in a lot of situations, but very definitely not all.
Biting the hand that feeds IT
