My PC now has some kind of redirect malware which redirects to canadaalltax.com on occasions.
to get removal help, see logs to assist in cleaning malware guide at top in viruses and worms forum section

comodo will conflict with avast if you install comodo firewall with antivirus
you have firewall in win XP and if you are behind a router with firewall that should be enough in my opinion … but there are lots of users that dont agree on that