If you cannot ping a Windows 7 box, don't just disable the Windows Firewall. See the following page describing how to enable the included ICMP Echo rule in the Windows Firewall:
http://www.fixya.com/support/r5359816-allow_ping_icmp_echo_request_windows_7
Note that I shut down the Windows Firewall service (net stop mpssvc) and this did not "re-enable" ping. I had to add the firewall rule. There may be another solution, but this solved my problem.
Rob