Difficulty pinging between Host and Guests

Hi

I want to establish network connectivity between my host OS (XPsp3) and my guests (CentOS5.5 and Windows 7).

So far I can ping between guests, but not from host to guest or guest to host.  When I try, I get a 'destination host unreachable' message. 

When I configured my VMs to begin with, I set them to 'Host-Only' and I need to keep them that way for the purpose of what I'm doing with them - is that the problem?

Ipconfig and ifconfig outs from all machines attached.

Bests

Adam