It is up to you if you want to use PCT or not. I certainly would NOT use the XP firewall as this is 1-way FW and too weak. There are other FW's out there that are better, such as AIS (Avast Internet Security), Online Armor (free or paid), Comodo (free or paid), Outpost (free or paid) to mention a few that are compatible with Avast.
This is your machine, so you need to do what you feel comfortable doing. We are just giving you suggestions based on our experience in helping many others, and in my case testing PCT FW (and the other FW's) as well. Keep in mind that with most security software, which includes FW's, you can usually
trial a software for 30 days prior to buying it to see if you like it and it plays well with your machine/software. Just print up the directions on how to uninstall it before you install it in case you decide you need to do this.
