The hospitals I have worked for use laptops with wireless networking. There are also Thin Clients that have wireless adapters. You can either use Windows Terminal Services or the newly released
Windows Hyper-V Virtual Server or application delivery like
Citrix Delivery Center.
We use VMWare's Virtual Desktop Manager and Virtual PC's that run in a pool. To connect to the Virtual PC's, we use the Wyse S10 Thin Clients -
Wyse Technology - Global Leader in Thin Computing. There are other vendors such as HP and shortly, Dell will have a Thin Client as well.
By the time it is all set up, it is no cheaper than purchasing individual PC's but deployment of a new Virtual PC and Thin Client is much easier than managing a physical computer.