So i'm trying to set up a pen test lab in virtual box on my windows 7 host.

I have 3 guest OS's installed:
1.) BackTrack5
2.) Centos 5 Server/Snort (My Snortbox)
3.) Win XP (Unpatched)

I have 3 Ethernet adapters created IP'S
192.168.191.1
192.168.127.1
192.168.56.1

My goal is to use BackTrack5 to nmap the Win XP guest and have the snort box sniff the network.

I'm new to networking and virtualization and I need help setting up my virtual network to get this to work. What should I do? All help appreciated

Centos:
Adapter1: NAT
Adapter2: Host-only
Adapter3: Internal Network

Backtrack:
Adapter1: Internal Network

XP:
Adapter1: Internal Network

Also take for granted I'm on a University Network with a ridiculous firewall so I need to stay all within the host