I use windows firewall but is it really that bad if so should I wait until avast releases version 5 or should I download something like PC Tools firewall or Comodo firewall pro.
The one key factor you don't mention is your OS as the XP firewall has zero outbound protection at all, for me that is not an option. I certainly wouldn't be waiting for any firewall to be released, avast or other wise on the off chance I didn't have a problem.
Any malware that manages to get past your defences will have free reign to connect to the internet to either download more of the same, pass your personal data (sensitive or otherwise, user names, passwords, keylogger retrieved data, etc.) or open a backdoor to your computer, so outbound protection is essential.
If you have the Vista firewall - You could also enable the outbound protection of the Vista firewall, but it isn't very friendly, is rule based and you have to create the rules. - Vista Firewall Control, check out this topic for some user friendly help for the Vista Firewall, Outbound protection,
http://forum.avast.com/index.php?topic=30234.0So as and when the avast firewall is released July probably you won't have been waiting for two months with limited firewall protection.
The other issue is that the avast firewall in the first instance is only likely to be released in an avast suite form and that may only be a paid option, so that is something which you should consider as that policy (sales/marketing) has yet to be confirmed.