I connect 7 tablet to a Windows 7 PC that has Thinstuff RDP software installed to allow up to 10 connections at once..
The tablets are connected over the wireless LAN and have good signal strength. The internet never drops out, only from time to time the tablets will disconnect from the RDP session or it will freeze up.
The PC is an i5 with 4GB of ram 64bit. Maybe adding extra ram will help