XP/VS Server and ThinClients
As XP/V S Server is fully compatible with Microsoft Terminal Server / Remote Desktop Services any Thin Client which works with those solutions can also be used with XP/VS Server.
So it should offer either rdesktop or FreeRDP as RDP client.
We would recommend using FreeRDP if possible.
Wyse C50LE Thin Client which with "Wyse Enhanced SUSE Linux Enterprise"
HP Thin Clients
As far as we know Dell currently does not offer any Thin Clients.