Question : Set up 1 VLAN on flat network, do I need to set up trunking?

I am running a flat network, that we have decided to set up 1 VLAN on for guest users in a different building.   I need this VLAN to have internet access only, no view to anything else.

Network::
1721 Router-->4000 HP procurve switch --> 2524 HP procurve switch (this is the 1 that gets the VLAN)

I am only have one 1 Ethernet port for the router, only 1 interface.

Do I need to use trunking between the router and the 4000 switch and the 2524 switch?  

Answer : Set up 1 VLAN on flat network, do I need to set up trunking?

is the hp 4000 a layer3 device