Avast 5 Firewall issue

[jackuars]

i have always been a true fan of avast and with the release of version 5 with superb layout and new features i have been impressed.
I am using Avast Internet Security 5.The issue am facing is that unlike most security suites it doesnt disable the windows firewall upon installation. The firewall is just turned on.I was curious about this coz its not good to turn on both firewall systems on the same computer.Isnt the firewall provided by Avast strong enough?  but i dont want to go back to Windows firewall

[DavidR]

The avast firewall is meant to be compatible with the windows firewall also running.