Ok so the thing with dumb terminals or thin clients, is that they can run on VERY limited hardware. Windows can run on Via 1ghz CPU systems, the thing with windows 7 Thin PC (or previous versions) is that they are usually installed on systems with a grand total of 1 or 2GB of storage (though you can find some with more but theres no point). These are locked down Operating systems that can essentially be frozen so that users cannot make any permanent changes unless authorized to do so. I cant say i've ever used file shares but i have used IE on these systems and i've also installed corporate version of Trend Micro on these.
Basically you, an admin, can sign in to this system with it unlocked. You can then create a RDP link and put it on the desktop or organize anything/shortcuts to the desktop or wherever and then you log off the admin account and when the user account is active, they are unable to modify anything, If they do manage to delete the shortcut or go in and change any settings that arent locked out (screen saver?), once the computer is restarted, any of those changes are undone and it goes back automatically to the profile configured by the admin.
When you power on the system, it automatically logs you into the user account and users usually dont ever see a login screen so they cannot even try to log in as administrator. So when the admin wants to sign in, you know that you have to go to log off from the start menu but while you click this log off button, you are holding the shift key which will bring you to the login prompt where you can type in administrator. Without pressing and holding the shift key you can hit log off, restart till you are blue in the face and it will continue to load directly into the "user" profile.
So basically is seen as an inexpensive way to get computers on your network, it makes management easier and cheaper as when you have a program, you only have to install it on the Remote Desktop Server and then all of the thin clients, once they RDC to the server, can access this recently installed application or network share, network printer etc. Also there is less network traffic because instead of a database being transferred over the network to all of the clients computers, it never has to leave the computer or data is only transferred between a couple of servers (which could utilize some high speed fibre if needed) and the only network traffic is the RDC commands as you type on your keyboard and move your mouse. This also makes troubleshooting easier because if one person is experiencing a problem, all of them are. So aside from making your life easier from an IT viewpoint, it also secures the network as some stranger cannot just walk up to a thin client computer and access Intellectual Property/Secured information as they are presented with a stripped down windows installation.
Then you configure your inactivity timeouts on the server which are pushed out to all of the clients, so if they sit idle for 5 minutes, you can boot that machine offline and require them to re-sign in and literally you can control anything the user can see or do all from one location.
So yes you should install this service on one of the current file servers. I would make sure this is a capable system as you will essentially have multiple concurrent windows sessions active (Depending on how many thin clients you use). But i've typically used HP Proliant Servers and i like the HP Thin Clients more than i any of the others, But if you have a Dell server, you dont have to use Dell thin clients, you can mix and match anything.
HP T5740 is the Thin client of choice for me. There are various configurations, Atom N280 CPU with 1GB or 2GB flash memory but just check out the link below as there are many out there.
Newegg HP thin Client List:
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&N=-1&isNodeId=1&Description=hp+thin+client
Keep in mind that these systems are from 200-500 on average, if you have Active Directory, all your machines need to have Windows Professional/Ultimate to join this domain. Now if you currently have Home Edition computers, you can still use those to connect to the RDC server with the remote desktop application.
That was long winded, hope it helps