Two Ubuntu Instances (Guest) networking with XP (Host) in virtual box v3.1.4

Question

So here is my current objective:

I need to create two guest instances of Ubuntu Desktop 9.10 in VirtualBox on a WindowsXP host. (This is needed for communications later on.) (this step is almost done)

I need to establish networking between all three OS's, the host and two guests (Guest1 -> Host -> Guest2).

I know that generally, to establish networking between Windows host and Ubuntu guest, we set up a bridge connection. But here there are two guests, and primarily I need networking between the two guests (Ubuntu to Ubuntu).

So will there need to be a change in tap0 and tap1 interfaces when we set up a bridge, or is there a better way to implement this?

Please explain the procedure