Can I use norton antivirus and windows defender at the same time on my cpu?

yes

Can I use norton antivirus and windows defender at the same time on my cpu?norton internet security 2008

Yes

Can I use norton antivirus and windows defender at the same time on my cpu?spyware removal

Yes

However, I would NOT recommend that at all. It will cause you to have a dramatic decrease in bandwidth because you now have two firewalls that they need to go through. Sticking with one program for a firewall and another for a virus scanner is usually the best bet on having solid security on a PC
i run defender [ that catches **** ] and Avast at the same time without degradation of any kind or conflict