I use norton for antivirus and firewall for viruses and for spyware I use pestpatrol, spybot, adaware, ewido, spysweeper, xoftspy and microsoft antispyware, you cannot have too many antispyware programs because one program will catch something another one might miss. I scan with a different one once a day and once a week I do a full system scan with all of them!
PS: I also use spyware blaster to help keep spyware from installing on my computer in the first place!