new malwarebytes anti-malware won't work with my computer

Hey, don't hesitate to continue the discussion in this thread if you run into problems with Avast, or patching vulnerabilities in XP. If you have firewall related questions then you'd probably be better off starting a new thread. Software firewall are complicated and require a broad range of computing knowledge to configure manually (I certainly wouldn't try it). Fortunately, most firewall apps come out of the box pre-configured to suit the needs of most users and therefore require very little input. Best of luck.