At one point in time, I had a month trial of Norton Antivirus. However, that was uninstalled shortly after the trial expired and well before I tried installing Avast.
Hmm, you´re in danger... NAV is the worse program to get rid of.
Let´s guide you to have success on it.
1. First (you have already done), use Control Panel, Remove NAV (you may stay with other Norton SystemWorks Suite). Boot.
2. Then, run RNAV2003. Answer no to the first question. Chose remove NAV2003. Boot
3. Install avast!. Boot.
4. You must "change" some Windows Registry keys... See DOS under XP / NAV
http://www.avast.com/forum/index.php?board=1;action=display;threadid=259;start=0The best way is "backup the original key", then backup again with another name and change the file. You´ll get a string with ... 00,00, ... in the middle and at the end. Symantec "mess" your registry! Let just the last group of zeros. In the middle, change to one: ... 00, ...
5. Boot.
6. Test your antivirus with eicar test.
I've got an Athlon 900 with 512MB RAM running Windows XP Pro with fairly standard settings. I've got a firewall built into my router that I use. Internal network is set up with NAT.
Sorry, what´s NAT?
Good luck. If you need more help, just ask...