Hello! I’ve been using the integrated Windows XP Firewall only (with Avast Free, MBAM etc. of course) for 5 years now. Is this enough or do I need a better firewall? And why? I don’t do internet shopping/banking, but I use torrents, eMule, MSN etc. All comments are welcome! 
Windows XP firewall does not offer outbound protection.
But, imho, if your computer is clean, you can stay with it.
Of course, there are better firewalls, freeware or AIS.
But you won’t find two persons that think the same here in avast forums :
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.
You wouldn’t call a door that only protected you from fire on one side a firedoor would you, I wouldn’t, I think the same of firewalls.
Thank you both for the answers! I have a clean system + my PC is quite old, so I’ll stay with Windows Firewall as Tech suggested.