Problem removing Anti-Virus

I’ve got a Dell Precision 3000 desktop running XP home edition. I have McAffee 8.5 enterprise running on the system and i want to replace it cos my license has expired. I used the add/remove programs but someone accidentally interrupted the uninstallation process. Now the system boots and i see McAffee virus scan running in the system tray, but its not there in the add/remove programs and i don’t see any McAffee services running. Is there any way i can remove the program completely? Someone suggested removing it from the registry but i’d only do that as a last resort. Any suggestions will be welcome.